This document summarizes an energy management study of the 2015 BMW i8 plug-in hybrid sports car. Some key points: - The BMW i8 features a 1.5L turbocharged gasoline engine and a 7.1 kWh lithium-ion battery pack. - The 96 kW electric motor on the front axle works with a 164 kW gasoline engine on the rear wheels for a total output of 260 kW. - Despite this performance, the i8 gets the equivalent of 94 mpg and can accelerate from 0-60 mph in 5 seconds. - The long, lightweight lithium-ion battery pack is located between the front and rear axles to keep the center of gravity low

1. Energy Management Study of BMW i8 E-Hybrid
Abu Nayeem, ID: 104319952; A.S.M. Ashraf Ahmed, ID: 103544063; MD Mahfuzur Rahman, ID: 104329740; Shourav Kumar
Das, ID: 104314362; Tawseef Quraishi, ID: 104337390.
Department of Electrical and Computer Engineering, University of Windsor, Windsor, ON, Canada.
Abstract- Automobile industry has come a long way in
developing technologies for better Electric Vehicle (EV) and
Hybrid Electric Vehicle (HEV). Hybrid electric vehicles
(HEVs) is the best option because it combines the power of
batteries and an internal combustion engine (ICE) which are
a promising mean of reducing emissions and fuel consumption
without compromising vehicle functionality and driving
performances. This paper presents the design of and
development of 2015 BMW i8 plug in hybrid sports car that
feature the 1.5 L turbocharged inline-3 gasoline engine and a
7.1 kWh lithium ion battery pack. The fuel intake aided by
hybridization is benchmarked to conventional Gasoline and
Diesel fueled vehicles. Though the automobile manufacturers
have reduced the greenhouse gases from the vehicle, a zero-
emission vehicle cannot be attained unless they produce an
electric vehicle (EV).
The 96 kW (131 hp) electric motor on the front axle works
in tandem with a turbocharged three-cylinder petrol engine
sending 164 kW (223 hp) through the rear wheels. Both units
are in-house BMW Group developments and generate an
aggregate system output of 260 kW (354 hp) and peak torque
of 550 Newton meters. That is enough to accelerate the BMW
i8 Concept Spyder from 0 to 100 km/h (62 mph) in five
seconds on the way to an electronically governed top speed of
250 km/h (155 mph). Despite this performance, the two-seater
burns just three liters of petrol per 100 kilometers (equivalent
to fuel economy of 94 mpg imp) in the European test cycle.
The electric motor sources its energy from a lithium-ion
battery which can be fully charged from a domestic power
socket in less than two hours. The high-output battery is
located in the energy tunnel between the front and rear axle
modules in order to keep the car’s center of gravity as low as
possible – and therefore to maximize the car’s dynamic
performance.
I. INTRODUCTION
An electric vehicle is an emission free, environmental
friendly vehicle. However, the electric vehicles remain
unpopular among the consumers due to their lack of
performance and their inability to travel long distances
without being recharged. So, vehicle that embraces both the
performance characteristics of the conventional automobile
and the zero-emission characteristics of the electric vehicles
are greatly being anticipated by the general consumers and the
environmentalists alike.
Technically, the quest for higher fuel economy is shaped by
two major factors: how efficiently a power train converts fuel
energy into useful power, and how sleek a vehicle is in terms
of mass, streamlining, tire resistance, and auxiliary loads. On
the other hand, vehicle functionality and comfort are shaped
by various other factors, many of which run counter to greater
fuel economy. Examples abound, from the way torque
converter sacrifices efficiency to provide better shift
smoothness and responsiveness to the wide variety of features
that add mass to a vehicle.
In extensive investigation is done on how battery
management system can be used to lengthen the lifetime of the
battery pack. The strategy is to monitor and charge the
batteries individually. As batteries in HEVs have very
dynamic discharging and charging cycles, it needs intelligent
system to maintain and prolong the batteries‟ life cycles. Due
to manufacturing inconsistencies and operational variations
each cell of battery can have different performance
characteristics.
The recommendation is to close monitoring and to control
the charging cycles. They also described the many possible
ways to recharge the batteries as such, constant voltage
charging and constant current charging. In most of the uses of
HEV, a single charger is used for entire battery pack. The
discussed intelligent system is to provide individual chargers
for each battery. This made possible due to a number of
advances that have allowed DC/DC converters that are used as
the battery chargers, to be considerably reduced in size and
weight. Every charger can be turned on independently and the
voltage limits can be adjusted remotely. However, there are
still needs of more research attention to improve the HEV
performance with lowest emission of carbon gasses which
severely affect the environment.
In this paper, we will mainly focus the different features of
BMW i8 plug in hybrid sports car, we discussed about the fuel
economy, performance, power, energy, weight, volume,
voltage and current constraints, battery chemistry, cell design,
electric motors, the liquid cooled lithium ion battery pack,
power electronics, functionality of the battery pack, challenges
and future prospects of this car.
II. HEV CONFIGURATIONS
A brief description about various HEV configurations
available in the market is presented. There are three main
configurations which are the series, parallel and the dual-mode
configurations and the explanation of each one of them with
their merits and demerits follows.
A. Series HEV Configuration
In series HEV configuration, only the electric motor is
connected to the drive train and thus the vehicle is entirely
driven by the electric motor. The Internal Combustion (IC)
engine drives an electric generator (commonly known as
alternator), which then deliveries the electric power to the
motor and battery pack.

2. Fig.1. Series HEV drive train [8]
If the battery is fully charged the IC engine will turn off. In
some circumstances, the electric power supply for the electric
motor can come both from the battery and the engine
generator set. Such that merely the electric motor is connected
to the drive train, the ICE can run at a top speed to run the
generator thus greatly reducing the emissions. The batteries
can be charged off-board, by external DC power link from the
electric-grid or the on-board, with the benefit of an alternator
and an ICE. In this format, it is plausible to design the
operation such that the IC engine never idles and thus the
overall emissions are reduced. The schematics of series HEV
is shown in Figure 1.
It can be seen that the IC engine is connected to the
alternator (generator) which in turn is connected to the battery
pack and electric motor through an electronic control unit.
This structure permits the electric motor to get its power from
either battery pack or the alternator or both as per the battery
state of charge and vehicle acceleration requirements.
Advantages:
 Most of the time low emission drive is possible
 As it is not connected directly to the drive train
engine can run more efficiently.
 The location of engine-motor set is flexible
 Suitability for short trips.
Disadvantages:
 The vehicle needs a full-sized electric generator, an
electric motor and an IC engine, each of which can
supply the required power for the vehicle.
 The automobile is only driven by the electric motor,
which places great constraints on the battery pack
and in particular requires large battery capacities.
 All three drive train components need to be sized for
maximum power for long distance, sustained, high
speed driving. This is because the batteries will
exhaust fairly quickly, leaving ICE to supply all the
power.
B. Parallel HEV Configuration
In the parallel HEV configuration there are two power
paths for the drive train, although one approaches from the
engine the other comes from the electric motor. While short
trips the electric motor can power the vehicle, during long
drives the ICE can power the vehicle. The vehicle can thus
have engine only, motor only, or a combination of engine and
motor mode of operation. The electric motor can likewise
support the engine during hill climbs and vehicle
accelerations, therefore the rating of the ICE can be reduced.
This configuration is illustrated in Figure 2.
In parallel HEV configuration, the drive train is connected
to the electric motor and engine through a mechanical
coupling or an angle gear. This automobile does not require a
generator (as in the case of series HEV configuration) and
they can be connected to an electric grid (off-board) for
recharging the batteries. The electric motor can be made to act
as generator via a mechanical clutch which can then be used
for regenerative braking. Both the gas-powered engine and the
electric motor can turn the transmission simultaneously, and
the transmission, of course, turns the wheels. The fuel tank
and gas engine and the batteries and electric motor connect
independently to the transmission as a consequence, in a
parallel hybrid both the electric motor and the gas engine can
provide power.
Fig.2. Parallel HEV drive train [8]
Advantages:
 The battery size can be small in this configuration, as
both the engine and motor are connected to the drive
train.
 Due to dual power sources the performance is very
much comparable to conventional vehicles.
 In this configuration the restrictions on the battery
pack and the electric motor are relaxed.
Disadvantages:
 When the battery pack charge is low the vehicle
cannot get full acceleration support from the electric
motor.
 The control intricacy rises significantly, because the
power flow has to be regulated and blended from two
parallel sources.
 The power amalgamation from the ICE and the motor
necessitates a complex mechanical device.

3. C. Dual Mode HEV Configuration
Dual mode hybrid vehicles are parallel hybrids, but
vary from them in the part that an alternator (generator) is
coupled to the IC engine that charges the battery. While
normal process, the IC engine turns both the drive train and
the generator, the battery packs through the electronic control
unit charges in return. In the course of full-throttle
acceleration, the electric motor acquires power from the
battery and assists the IC engine to attain the requested
acceleration. A full size electric motor is selected, which uses
the ICE only for charging the battery and occasionally for
rotating the wheels, can decrease exhaust emissions and this
can be achieved with the help of a mechanical clutch. This
configuration displays dual capability and hence the name
dual mode HEV configuration. The schematic of the dual-
mode HEV configuration is shown in Figure 3.
Fig.3. Dual Model HEV drive train [8]
III. TYPES OF DEGREE OF HYBRIDIZATION
Parallel and combined hybrids can be categorized depending
upon how balanced the different portions are at providing
motive power. In specific cases, the combustion engine is the
dominant portion; the electric motor turns on only when a
boost is needed. Others will just run on electric system.
A. Strong hybrid
A full hybrid EV can run on just the engine or the
batteries or a combination of both. For battery-only operation
a huge, high capacity battery pack is needed. Examples: The
Toyota Prius, Lexus and Auris are full hybrids, as these
vehicles can go on battery power alone. Hybrid Synergy Drive
is the Toyota brand name for this technology. A computer
manages all operation of the complete system, determining if
engine, motor or both are running. The ICE will be shut off
when the electric motor is sufficient to provide the power.
B. Medium hybrid
Motor assist hybrids use the engine for primary
power, with parallel connected torque-boosting electric motor
to a largely conventional powertrain. EV method is only
probable for a very narrow period of time, and this is not a
regular mode. Associated with full hybrids, the sum of
electrical power needed is minor, therefore the dimension of
the battery system can be reduced. The electric motor which is
fixed between the engine and transmission is basically a very
huge starter motor, which functions not only when the engine
needs to be turned over but also when the driver accelerates
and requires extra power. The electric motor is also used to
restart the combustion engine, giving the same aids from
shutting down the main engine, while the improved battery
system is used to power accessories. During regenerative
breaking the electric motor is a generator.
Fig.4. Overview of types of degree of hybridization [9]
C. Mild hybrid / Micro hybrid
Mild hybrids are essentially conventional vehicles with
oversized starter motors, letting the engine to be switched off
whenever the car is cruising, braking or stopped. Yet restart
swiftly and cleanly. During restart the bigger motor is used to
spin up the engine to operating rpm speeds before injecting
any fuel. This idea is not distinctive to hybrids. The motor is
used for regenerative braking to recollect energy in other
hybrids. But there is no help from the motor and no EV mode.
Therefore, many consumers do not consider them as hybrids,
since there is no electric motor to drive the car. These vehicles
do not attain the fuel economy of real hybrid cars.

4. D. Plug-in hybrid
All the previous hybrid architectures could be grouped
within a classification of charge sustaining: the energy storage
system in these vehicles is designed to remain within a fairly
confined region of state of charge (SOC). The hybrid driving
force algorithm is designed so that on average, the SOC of
energy storage system will return to its initial condition after a
drive cycle. A plug-in hybrid electric vehicle (PHEV) is a full
hybrid can run in electric-only mode with larger batteries and
the ability to recharge from the electric power grid. Their key
advantage is that they can be gasoline independent for
everyday driving, but also have the extended range of a hybrid
for long trips. Grid connected hybrids can be designed as
charge depleting: part of the ―fuel‖ consumed during a drive is
delivered by the usefulness and preference at night. Fuel
efficiency is then calculated based on actual fuel consumed by
the ICE and its gasoline equivalent of the kWh of energy
delivered by the utility during recharge. The "well-to-wheel"
efficiency and emissions of PHEVs compared to gasoline
hybrids depends on the energy sources used for the grid utility
(coal, oil, natural gas, solar power, hydroelectric power, wind
power, nuclear power). In a serial Plug-In hybrid, the ICE
only serves for supplying the electrical power via a coupled
generator in case of longer driving distances. Plug-in hybrids
can be made multi-fuel with the help of electric power
enhancement by diesel, biodiesel, or hydrogen.
IV. LITHIUM ION BATTERY PACK FOR BMW I8
The BMW i8 is plainly engineered around its battery pack,
which is about the dimensions and form of a tipped-over
grandfather clock. To achieve the i8’s targeted 22-mile
electric-driving range; BMW assembles 96 Samsung-supplied
prismatic lithium-ion battery cells into a 57.5 x 14.4 x 13.0-
inch die-cast aluminum box.
Even though the battery pack’s total energy capacity is
7.1 kWh, normal usage is limited to 5.2 kWh to ensure a
satisfactory service life. To protect the 216-pound pack
against impact damage and to make it readily removable for
service, it—and its aluminum box—runs lengthwise down the
middle of the car. It could be merely so wide and so tall to
avoid overwhelming the interior, so as a result, it became very
long to deliver the desired energy capacity and maintain
sufficient space for people.
Fig.5. Battery Pack of BMW i8.
Tacking a powertrain (one gas, one electric) to each end of
the box yields a 110.2-inch wheelbase, only little bit shorter
than what’s found in BMW’s 4-series coupe.
Fig.6. Battery box structure of BMW i8.
The battery box plays no substantial structural role;
attaching it rigidly to the surrounding structure would frustrate
its removal for service. Thus high, thick sills are necessary to
provide the requisite bending and torsional rigidity, as are
formed-aluminum structural reinforcements throughout the
molded-carbon-fiber central body. Supplement together the
13.0-inch width of the battery box, adequate space for two
front occupants and you get an overall width of 76.5 inches,
more than five inches greater than a Porsche 911’s. [10]
V. CELL CONCEPT OF BMW I8
TECHNICAL CONCEPT – Modular kit HW: same
electronic components in both systems. Modular kit SW: same
software and algorithms in both systems, diversity by
calibration.
A. TECHNICAL CONCEPT – CELL MODULE.
Cell number per module (12 vs. 16): trade-off between
package, electronic components and transport regulations Cell
module is a serviceable unit. Validation on module level
guarantees high quality and reduced costs. [11]
Fig.7. Cell construction of BMW i8.

5. VI. BMW I8 CHARGING
For the i8 Inductive charging provides reliable, wear-free
and user-friendly EV battery charging using a magnetic field,
without the need for a hard-wired connection between the
vehicle and the power source. The system contains a primary
and a secondary coil. The primary coil is fitted in a base pad
underneath the vehicle, for example on or embedded in the
garage floor.
The secondary coil is integrated in the underside of the
BMW i8. As soon as the vehicle is positioned over the base
pad and the charging process begins, an alternating magnetic
field is generated which transmits electricity between the
coils. The electricity is transmitted without cables or contacts
across a gap of several centimeters, at a charge rate of 3.3 kW.
The high-voltage battery of the BMW i8 can be fully
recharged in less than two hours using this system – which is
approximately the same amount of time required with a wired
connection. Future inductive charging systems with a higher
charge rate of 7 kW will also allow the larger batteries of all-
electric vehicles, such as the BMW i3, to be fully recharged
overnight. In typical accessible areas immediately next to the
vehicle, the electromagnetic field strength during inductive
charging is well below the existing regulatory limits. The
electromagnetic radiation is less than that emitted by an
induction hotplate on a kitchen stove.
VII. TECHNICAL DATA [12]
A. Engine Drive
System output in kW
(horse power)
266 (362)
Electric motor:
Output in kW
96
Electric motor: Max.
torque in Nm
250
Internal combustion
engine: Cylinders/valves
3/4
Internal combustion
engine: Capacity in cubic
cm
1,499
Internal combustion
engine: Stroke/bore in
mm
94.6/82.0
Internal combustion
engine: max. output in
kW (horse power) at
1/min
170 (231)/5,800
Internal combustion
engine: max. torque in
Nm at 1/min
320/3,700
Internal combustion
engine: Compression
ratio : 1
9.5
B. Consumption
Maximum speed on
purely electric power in
km/h
120
Maximum speed in
km/h
250
Acceleration from 0–
60 km/h on purely
electric power in seconds
4.5
Acceleration from 0–
100 km/h in seconds
4.4
Elasticity from 80–
120 km/h in seconds (4th
gear)
3.4
Elasticity from 80–
120 km/h in seconds (5th
gear)
4.0
C. Consumption
CO2 emissions in
g/km
49
CO2-Effizienz A+
Consumption
combined in l/100 km
2.1
D. Range and charge time
Electric range in km 37
Customer-orientated
range in km
up to 30
Maximum total range
in km
440
Gross capacity of
lithium-ion battery in
kWh
7.0
Charging time of
high-voltage battery in h
at 3.7 kW/12 A (80 %)
2.5
Charging time of
high-voltage battery in h
at 16 A (Wall box) (80
%)
2
E. Weight
Unlading weight in
kg
1,485
Permitted total weight
in kg
1,855
Vehicle load capacity
in kg
370
Permitted front/rear
axle load in kg
895/995

6. F. Power Train
The powertrain of the BMW i8 actually comprises of two
distinct power sources. Up front, an electric motor powers the
front wheels, and at the rear, a high-output turbocharged three-
cylinder drives the rear wheels [13].
Fig.8. BMW i8 powertrain [12]
The arrangement gives the i8 the capability to run uniquely
on electricity, as a sporty hybrid, or with equally operating
together for maximum performance. The independently
operable set of the two powertrains makes the BMW i8 what
engineers term a "through-the-road" hybrid, with each mode
of propulsion synchronized not mechanically but via control
software when they are used together for all-wheel drive and
supreme performance [13].
G. BMW i8 electric motor
The electric motor up front is rated at 96 kilowatts (131
horsepower) and 184 pound-feet of torque; it's used for all-
electric running at speeds up to 75 mph. In the rear, the i8 is
the first BMW to practice the company’s new 1.5-liter
turbocharged three-cylinder engine, rated at 231 horse power
and 236 pound-feet of torque. (It's also used in the new third-
generation MINI Cooper, in a lower state of tune.) The engine
drives the rear wheels through a six-speed automatic
transmission.
Fig.9. BMW i8 electric motor [12]
BMW figures an electric range of up to 22 miles in "Max
E-mode", but the electric motor also provides "boost" to the
engine when the car is running in its uppermost performance
"Sport" mode. The defaulting mode, known as comfort, uses
each powertrain or both in a well-organized manner, and the
EPA rates the i8's total united range between the charged
battery and the gasoline tank at 330 miles [13]. In
accumulation to the three driving modes-- Comfort, Max E-
Mode and Sport--the first two can be driven using the Eco-Pro
function, which increase efficacy and range by capping
acceleration and other energy uses.
H. BMW i8 battery pack
BMW i8 energy originates from a liquid-cooled lithium-
ion battery pack with a working energy capacity of about 5
kilowatt-hours, attached in the channel between the seats,
giving the entire car a low, sleek profile [13].
I. BMW i8 mileage
The EPA rates the i8's electric range at 15 miles, and gives
it a rating of 76 miles per gallon equivalent when running
electrically. Miles per gallon equivalent measures the
detachment that a car can mobile on the same quantity of
energy as that contained in 1 gallon of gasoline. When running
as a gasoline hybrid, the BMW i8 gets a fuel competence
rating of 28 mpg--decent for a high-performance sport coupe,
but lesser than equivalent ratings for more pedestrian plug-in
hybrid sedans and hatchbacks [13].
VIII. BATTERY CHEMISTRY
Lithium ions move from anode to cathode during discharge
and from cathode to anode in the charging time. Battery
performance can be affected by using different materials of
anode and cathode. Higher capacity materials are required to
provide greater life cycle, charge life span and energy density.
For commercial use Graphite has been the choice for
anode with typical 1st generation lithium ion chemistry
working as follows:
Fig.10. Battery chemistry of Li-ion battery [14]
Overall reaction on Li-ion cell
C+ LiCoO2 =LiC6+Li0.5CoO2 [14]
At the cathode
LiCoO2 - Li+
-e-
= Li0.5CoO2=143mAh/g [14]
At the anode
6C + Li+
+e-
= LiC6=372mAh/g [14]

7. Different materials have been tested but Silicon provides
the highest gravimetric capacity (mAh/g). The volumetric
capacity (Wh/cc) of Silicon increases resulting from addition
of lithium which is now considerably higher than that
associated with carbon anode materials. Silicon holds great
promise for future Lithium ion batteries but charge discharge
cycle life traditional silicon-based anode is typically short.
The table below shows comparison to Li-ion (graphite
anode) to other battery chemistry.
TABLE I. COMPARISON TO LI-ION (GRAPHITE ANODE) TO
OTHER BATTERY CHEMISTRY [15].
Characteristics LiCoO2(LCO) LiFePO4(LFP) SLA NiCd NiMH
Nominal
voltage per cell
3.7 2.5-3.61
2.015
1.215
1.215
Specific
Energy(Wh/kg)
175-2001,15
60-1101
30-4015,16
35-8015,16
55-11015,17
Energy
Density(Wh/l)
400-6401
125-2501
50-9015,16
100-
15015,16
16016
-42018
Cycle Life(to
80% original
capacity at
100% DOD)
500+1
1000+1
200-
300(upto
400 at
80%
DOD)19
300-100015
500-100015
Calendar
Life(years)
>51
>51
2-815
5-715
5-1015
Ambient
temperature
during
charge(◦
C)
0-451
0-451
-40-5015
0-4015
0-4015
Ambient
temperature
during
discharge(◦
C)
-20-601
-30-601
-40-6015
-20-7015
-20-6515
Self discharge
capacity loss
per month
2-10% 2-10% 4-8% 15-20% 15-
30%(conv)
2% (adv)
Memory effect No No No Yes Yes Less
than NiCd
Toxic Metals None None Lead Cadmium None
Battery
management
system
required
Yes Yes No No No
IX. PROPOSED HYDROGEN FUELED BATTERY FOR BMW I8
BMW has unveiled a new prototype of BMW I8 with
hydrogen fuel cell powered version. So the general idea for
Hydrogen fuel cell is described briefly below.
Hydrogen fuel cell converts chemical energy stored by
hydrogen fuel into electricity. Hydrogen gas is supplied to the
anode of the fuel cell coated with platinum which acts as a
catalyst to break down into photons and electrons.
Reaction at the anode [18]
2H24H+
+4e-
Reaction at the Anode [18]
O2+4H+
+4e-
2H2O
When the circuit is connected between anode and cathode
then electron can travel through the circuit and provide power
to any load that is connected as a part of circuit. [18]
X. VOLTAGE AND CURRENT CONSTRAINS OF LITHIUM ION
BATTERY
Charging to lower voltage will prolong the life cycle of the
battery but it causes a major capacity reduce. If we charge a
4.2 volt battery to 4.1 volt, then its causes 10% or larger
reduction in capacity. Proper voltage regulation is needed for
safely charging lithium ion batteries; the tolerance for
overcharging can be 50mvolt or less. But discharging the
battery below 2.5-3volrage /cell can damage it permanently or
cause short circuiting.
Fig.11. Approximate current and voltage during li-ion
charging. [16]
There are two stages of charging where current and voltage
changes. At stage 1 voltage rises at constant current whereas
at stage 2 voltages reach to maximum and current decreases.
[15]
The maximum charges and discharge current for battery
packs is are is limited between 1c and 2C. [17] Charging cells
in series of Lithium ion battery needs circuitry to balance
voltage between cells, so that no individual cell exceeds its
maximum voltage. So it requires protection circuit to maintain
voltage and current within safe limits.
XI. POWER ELECTRONICS & CONTROL OF BATTERY PACK
The BMW i8, first introduced as the BMW Concept Vision
Efficient Dynamics, is a plug-in hybrid sports car developed
by BMW. The 2015 model year BMW i8 has a 7.1 kWh
lithium-ion battery pack that delivers an all-electric range of
37 km (23 mi) under the New European Driving Cycle
(NEDC). Under the United States Environmental Protection
Agency (EPA) cycle, the range in EV mode is 24 km (15 mi)
with a small amount of gasoline consumption.
The BMW i8 can go from 0–100 km/h (0 to 60 mph) in 4.4
seconds and has a top speed of 250 km/h (155 mph). The
BMW i8 has a fuel efficiency of 2.1 L/100 km (134.5 mpg-
imp; 112.0 mpg-US) under the NEDC test with carbon
emissions of 49 g/km. EPA rated the i8 combined fuel
economy at 76 equivalents (MPG-equivalent) (3.1 L gasoline
equivalent/100 km; 91 mpg-imp gasoline equivalent).
The initial turbodiesel concept car was unveiled at the 2009
International Motor Show Germany. The production version
of the BMW i8 was unveiled at the 2013 Frankfurt Motor

8. Show. The i8 was released in Germany in June 2014.
Deliveries to retail customers in the U.S. began in August
2014. Global cumulative sales totaled over 5,700 units through
September 2015. The top selling markets are the United
States, the UK and Germany .[1]
First plug-in hybrid vehicle from the BMW Group and
world’s most forward-looking sports car; revolutionary
interpretation of BMW’s hallmark driving pleasure;
groundbreaking premium character clearly defined in terms of
sustainability. [2]
Plug-in hybrid system developed and produced by the
BMW Group represents the latest development stage of
Efficient Dynamics; debut for three-cylinder gasoline engine
with BMW TwinPower Turbo technology, displacement: 1.5
liters, output: 170 kW/228 hp, maximum torque: 320 Nm (236
lb-ft); power sent to the rear wheels via a six-speed automatic
gearbox; model-specific hybrid synchronous electric motor,
output: 96 kW/129 hp, maximum torque: 250 Nm (184 lb-ft);
power channeled through the front wheels via a two-stage
automatic transmission; lithium-ion high-voltage battery with
liquid cooling and usable capacity of 5 kWh. [2]
First combination of BMW TwinPower Turbo and BMW
eDrive technology plus intelligent energy management
produce system output of 266 kW/357 hp (max. torque: 570
Nm / 420 lb-ft) and give the BMW i8 the performance
characteristics of a pure-bred sports car (0 –60 mph in 4.2
seconds) combined with fuel economy and emissions
comparable to a small car - EU fuel consumption: 2.5 litres
per 100 km / 94 mpg (US); ―glued-to-the-road‖ AWD driving
experience with torque distribution geared towards optimized
dynamics .[2]
Driving Experience Control switch and eDrive button allow
driver to choose from five driving modes; range of up to 35
kilometers (22 miles) on electric power alone and a top speed
of 120 km/h (75 mph); COMFORT mode offers optimum
balance between dynamics and efficiency; combined range in
everyday conditions: over 500 kilometers (310 miles); SPORT
mode with ultra-intense boost function provided by the
electric motor; ECO PRO mode can be used in both all-
electric mode and hybrid mode. [2] It is shown in figure 2
which shows the whole console of BMW i8. [7] Five driving
modes allow drivers to adjust efficiency and dynamic
performance as desired – at the touch of a button. [2]
First combination of BMW TwinPower Turbo and BMW
eDrive technology plus intelligent energy management
produce system output of 266 kW/357 hp (max. torque: 570
Nm / 420 lb-ft) and give the BMW i8 the performance
characteristics of a pure-bred sports car (0 –60 mph in 4.2
seconds) combined with fuel economy and emissions
comparable to a small car - EU fuel consumption: 2.5 litres
per 100 km / 94 mpg (US); ―glued-to-the-road‖ AWD driving
experience with torque distribution geared towards optimized
dynamics. [2]
Fig.12. An overview of BMW i8 [4].
The three-cylinder combustion engine in the BMW i8
develops 170 kW/231 hp and drives the rear wheels, while the
96 kW/131 hp electric motor draws its energy from a lithium-
ion battery, which can be charged from a conventional 110
volt power outlet as well as a 220 volt electric vehicle charger,
and sends its power to the front axle. This bespoke plug-in
hybrid system, developed and produced by the BMW Group,
enables a range in everyday driving of up to 35 kilometers
(approx. 22 miles) and a top speed of 120 km/h (approx. 75
mph) on electric power alone, coupled with a ―glued-to-the-
road‖ all-wheel driving experience headlined by powerful
acceleration and a dynamically-biased distribution of power
through enthusiastically taken corners. The more powerful of
the two power sources drives the rear wheels and uses the
electric boost from the hybrid system to deliver hallmark
BMW driving pleasure while at the same time offering
groundbreaking levels of efficiency. The sprint from 0 to 60
mph takes just 4.2 seconds, yet average fuel consumption – as
calculated in the EU test cycle for plug-in hybrid vehicles –
stands at the equivalent of 94 miles per US gallon from launch
.[2]
As not only a new car, but an all-new concept, there’s little
independent data to verify how reliable the i8 will be.
However, BMW as a brand has only an average record,
finishing 13th out of 27 manufacturers in the 2014 Driver
Power customer satisfaction survey. [3]

9. Fig.13. BMW i8 console [7]
The i8’s three-year, unlimited-mileage warranty is better
than that offered by rival Porsche, which covers its cars for
just two years. In addition, the i8’s battery is covered by an
eight-year or 100,000-mile warranty, designed to provide
peace of mind for owners investing in this relatively new
technology. Due to having few moving parts, electric motors
also tend to be very durable. [3]
When a car looks this fast, it better live up to its
appearance. The BMW i8 does just that, with help from its
powerful, yet efficient TwinPower Turbo 3-cylinder
combustion engine and its innovative electric motor. Together,
these two engines work in tandem for uninterrupted
acceleration from a standstill with a total system output of 420
lb-ft of torque and 357 horsepower. [6]
The car’s second power source is a hybrid synchronous
electric motor specially developed and produced by the BMW
Group for the BMW i8. The motor develops maximum power
of 96 kW/131 hp and produces its maximum torque of around
250 Newton meters (184 lb-ft) from standstill. Power is
instantly available –an advantage of electric motors- from 0
rpm and remains available into the higher load ranges. Credit
for the linear power delivery, which extends right up to the
high end of the rpm range, goes to a special motor design
principle exclusive to BMW i. BMW eDrive technology
refines and improves on the principle of the permanently
excited synchronous motor with a special arrangement and
dimensions for the torque-producing components. This results
in a self-magnetizing effect normally confined to reluctance
motors. This additional excitation ensures that the
electromechanical field generated when current is applied
remains stable even at high rpm. [2]
As well as providing a power boost to assist the gasoline
engine during acceleration, the electric motor can also power
the vehicle by itself. Top speed is then 120 km/h (approx. 75
mph). The BMW i8 has a maximum driving range in this
emission-free, virtually soundless, all-electric mode of up to
35 kilometers (approx. 22 miles). The motor derives its energy
from the lithium-ion battery which is centrally mounted
underneath the floor of the vehicle. This model-specific
version of the high-voltage battery was developed and
produced by the BMW Group. It has a liquid cooling system,
offers a maximum usable capacity of five kilowatt hours and
can be recharged from a conventional 110 volt AC power
outlet, at a BMW i charging station, or at a public EV
charging station. [2]
Fig. 14. Cut-away view of an air foil bearing-supported
turbocharger [5]
The BMW i8’s vehicle concept and powertrain control
highlight its progressive, revolutionary character. The BMW
i8 always achieves the optimal balance between dynamic
performance and efficiency, whatever the driving situation.
For example, the battery can also be recharged via the electric
motor while decelerating. In addition to this, when power
demands allow, the high-voltage battery is recharged by the
electric motor. The high-voltage starter-generator, responsible
for starting the combustion engine, can also be used as a
generator to charge the battery, the necessary power being
provided by the BMW TwinPower Turbo engine. These
various processes help ensure that the BMW i8 always has
sufficient energy on board to power the electric drive system.
The all-electric driving range is sufficient to cover most urban
driving requirements. Out of town, the BMW i8 delivers
impressively sporty performance with extreme efficiency,
thanks to the electric motor’s power-boosting support for the
gasoline engine. With such versatility, the BMW i8 belongs to
a new generation of sports cars which unites exciting
performance with cutting-edge efficiency – to enhance both
driving pleasure and the sense for sustainability. [2]
An extensive range of products and services from 360°
ELECTRIC are available for the BMW i brand’s second
series-produced model. The 360° ELECTRIC portfolio
focuses on home charging, charging at public charging
stations, keeping drivers on the road and integration into
innovative mobility concepts. As such it promotes the
comfortable, reliable and flexible utilization of electric
mobility. This package of features also helps to make
maximum use of the efficiency potential inherent in the
vehicle concept and drive system technology of the BMW i8.
Maximizing the use of the electric motor and feeding
renewably generated electricity into the high-voltage battery

10. significantly improves the CO2 rating of the plug-in hybrid
sports car. [2]
The BMW i8 is equipped as standard with an integrated
SIM card which provides the intelligent connectivity required
to use the mobility services from BMW Connected Drive. It
also introduces navigation services specially developed to
enhance electric mobility – such as the Range Assistant with
dynamic range map – alongside familiar features, including
the Concierge Services information facility, the Intelligent
Emergency Call function and the Online Entertainment music-
on-demand service. Moreover, drivers can use the BMW i
Remote app to share information with their car at any time
using their smartphone. For example, they can use their phone
to control the charging process for the high-voltage battery
and, while that is happening, also oversee the advance
preparation of the vehicle before a journey. [2]
XII. CHALLENGES & FUTURE PROSPECTS
BMW i8 stands for the creation of pure-bred vehicle
concepts, sustainability throughout the value chain,
complementary mobility services and a fresh understanding of
premium defined squarely in terms of sustainability. And now
the BMW Group can unveil the BMW i8 – a new, cutting-edge
generation of sports car. The second model unveiled by the
new BMW i8 brand combines a plug-in hybrid drive system
with a passenger cell made from carbon-fiber-reinforced plastic
(CFRP) and an aluminum frame for the combustion engine and
electric motor, the battery pack and the suspension. [2]
The perfect balance of performance and fuel consumption:
the BMW i8 represents an exciting new landmark in Efficient
Dynamics.
The BMW i8 offers a revolutionary and future-focused
interpretation of BMW’s signature driving pleasure – and in so
doing, makes its case as the world’s most progressive model in
the sports car segment. The plug-in hybrid drive system
developed and manufactured by the BMW Group especially
for the BMW i8 represents a new stage of evolution in the
Efficient Dynamics development strategy. [2]
The development of BMW i cars follows a revolutionary
approach, a strategy focusing on the creation of premium cars
purpose-designed to be powered by purely electric or plug-in
hybrid drive systems. This electric drive technology (packaged
under the BMW eDrive banner) is therefore a central
component of the vehicle concept – in contrast to the
―conversion‖ model, where vehicles are retrofitted with electric
drive systems. Characteristic BMW driving dynamics coupled
with emission-free mobility, precise energy flow management,
pioneering design, intelligent lightweight construction and
production processes that preserve energy and resources come
together to mutually complementary effect to form the
innovative, sustainability-led premium character of BMW i
cars. [2]
REFERENCES
[1] http://insideevs.com/first-bmw-i8-deliveries-scheduled-june-final-
perfomance-fuel-consumption-figure-releaseed/
[2] https://www.press.bmwgroup.com/usa/pressDetail.html?title=the-bmw-
i8-%E2%80%93-ushering-in-a-new-era-of-sustainable-performance-
priced-from-135-700-in-the-
us&outputChannelId=9&id=T0145577EN_US&left_menu_item=node_
_6728
[3] http://www.telegraph.co.uk/cars/bmw/i8/
[4] http://www.bmw.ca/en/all-models/bmw-i/i8/2015/intro.html
[5] https://en.wikipedia.org/wikiTurbocharger
[6] http://www.bmwusa.com/bmw/bmwi/i8
[7] https://en.wikipedia.org/wiki/BMW_i8
[8] M.H. Ullah, T.S. Gunawan, M.R. Sharaif and R Muhida, ―Design of
Environmental Friendly Hybrid Electric Vehicle,‖ International
Conference on Computer and Communication Engineering (ICCCE),
IEEE 2012, pp 544 – 548
[9] Wroclaw University of Technology ―Hybrid Electrical Vehicles‖,
Retrieved from:
http://www.ae.pwr.wroc.pl/filez/20110606092353_HEV.pdf
[10] http://www.greencarreports.com/news/1100792_all-hydrogen-fuel-cell-
cars-are-compliance-cars-for-now/page-2
[11] http://blog.caranddriver.com/all-about-the-batteries-baby-2015-bmw-i8-
battery-pack-dictated-its-entire-design/
[12] http://www.bmw.com/com/en/newvehicles/i/i8/2014/showroom/tetechni
c_data.html
[13] http://www.thecarconnection.com/overview/bmw_i8_2015
[14] http://www.nexeon.co.uk/about-li-ion-batteries/
[15] Lithuim ion battery overview , technical notes issue 10 ,May 2012
[16] http://www.lightingafrica.org/resources/briefing-notes.html
http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries
[17] http://batteryuniversity.com/learn/article/is_lithium_ion_the_ideal_batte
ry
[18] http://sepuplhs.org/high/hydrogen/hydrogen.html