| Mitsubishi Motors has chosen to center its development of next-generation electric vehicle technology on in-wheel motors, which minimize drivetrain space requirements, and on lithium-ion batteries with their superior specific energy characteristics. Dubbed the Mitsubishi In-wheel motor Electric Vehicle (MIEV) concept, the company is currently working on a test vehicle that utilizes these core technologies. The MIEV concept offers a very promising clean propulsion solution in this the century of the environment and the company also envisages its application to hybrid electric and fuel cell vehicles. |  Colt EV (in-wheel motor test vehicle) |
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In-wheel motor |
| Greater freedom in layout design Placing the drive system in the wheels gives the designer a much freer hand in developing the layout of the vehicle. The space-saving features of the in-wheel motor drive system will facilitate the conversion of IC engine-powered vehicles into hybrid electric vehicles and also makes it easier to provide room for space-consuming components such as fuel cell stacks and hydrogen tanks in fuel cell vehicles. |
 In-wheel motor (on Colt EV) |
MIEV core technologies - the in-wheel motor and lithium-ion batteries - are applicable to hybrid and fuel cell EVs.
| Further evolution of all-wheel control technology Fitting an in-wheel motor to each wheel produces an all-wheel drive system that requires no transmission, drive shafts, differential gears or other complex mechanical components. In addition, the in-wheel motor makes it possible to control drive torque and braking force independently and with great precision at each wheel. As such, the in-wheel motor holds much promise in terms of further evolution of Mitsubishi's all-wheel control technology that enjoys high critical acclaim on such production models as the Lancer Evolution and Pajero. The company is currently working on a new 50kW in-wheel motor with outer rotor design to be used to power each wheel on a high-performance 4WD test vehicle. |
 The use of an outer rotor boosts maximum torque and eliminates the need for a reducer unit. The reduction in overall size also allows the motor to be fitted in the front wheels. |
Lithium-ion battery technology |
Lithium-ion battery technology offers significant performance benefits in terms of specific energy and life over other types of rechargeable batteries. Mitsubishi Motors has already built several test vehicles using lithium-ion battery systems, including the Mitsubishi HEV in 1996, the FTO-EV in 1998 and the Eclipse EV in 2000. The FTO-EV set a multiple-charge 24-hour distance world record on a proving ground, while the Eclipse EV covered over 400 km on public roads on a single battery charge. These and other testing programs have enabled the company to verify the practical applicability of this type of battery.
Lithium-ion battery technology has made major advances in performance over the past few years and holds much promise in terms of higher speeds, extended cruising range and weight reduction for electric, hybrid and fuel cell vehicles.
Lithium-ion battery technology has made major advances in performance over the past few years and holds much promise in terms of higher speeds, extended cruising range and weight reduction for electric, hybrid and fuel cell vehicles.
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Major advances in lithium-ion battery technology over the last five years bring the day of truly practical EVs much closer. |
 14.8V battery module comprising four 3.7V cells. |
 325V battery pack made up of 22 modules arranged in series. |
Colt EV in-wheel test vehicle |
Mitsubishi Motors Colt EV in-wheel motor research vehicle is based on the production Colt compact car. After removing the IC engine, fuel tank and transmission, in-wheel motors are fitted in the rear wheels and are powered by an under-floor lithium-ion battery system. Colt EV is currently undergoing extensive testing at the company's proving ground facility.
Colt EV is scheduled to start an on-road testing program to identify and resolve any problems unique to the in-wheel motor drive system vehicle, including any deterioration in road holding and ride comfort due to increases in unsprung weight, as well as reliability and durability issues in the in-wheel motor system and its peripheral components (suspension, wheels, tires).
Colt EV is scheduled to start an on-road testing program to identify and resolve any problems unique to the in-wheel motor drive system vehicle, including any deterioration in road holding and ride comfort due to increases in unsprung weight, as well as reliability and durability issues in the in-wheel motor system and its peripheral components (suspension, wheels, tires).
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Colt EV specifications |
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