2012 Mitsubishi i chassis

Compact in size yet amazingly space efficient and structurally sound, the 2012 North American-spec Mitsubishi i 100% electric-powered vehicle is based on a platform that has served tens of thousands of consumers well in markets around the globe.

From such diverse locales (both culturally and geographically) as the Pacific Rim to the Middle East, the United Kingdom to Australia, owners have come to love the affordability and practicality that the gasoline-powered version of the Mitsubishi i has to offer. The same can be said of the battery electric version of the vehicle as well: In less than two years, the Mitsubishi i EV has already sold over 10,000 units in its home market and across Europe.

Redesigned Body for Increased Roominess
The North American spec 2012 Mitsubishi i is both wider and longer than its Japanese and European-spec predecessors. While much of its additional length (145 in. overall – an increase of nearly 8 in.) can be attributed to the accommodation of larger bumpers front and rear, the vehicle’s interior cabin width has grown by about 4.5 inches when compared to that of the European-spec car, making for a noticeably increased amount of elbow room for both the vehicle's front and rear occupants.

Redesigned Suspension System to Better Suit North American Drivers

Upgraded Suspension System to Better Suit North American Drivers
Consisting of a MacPherson strut layout in front and a 3-link De dion type at the rear, the suspension system of the North American-spec 2012 Mitsubishi i offers a compliant and well-balanced degree of ride comfort and handling stability.

Front suspension and steering components of the 2012 Mitsubishi i

Front Suspension
Making use of the popular MacPherson strut design, the front suspension of the North American-spec 2012 Mitsubishi i has been modified to better suit both U.S. and Canadian drivers.

The vehicle’s pull straight-line stability has been improved by increasing both the caster angle and the caster trail while decreasing the amount of kingpin offset when compared to the European version.

Rear suspension of the 2012 Mitsubishi i
 
Rear Suspension
Already a proven and well-sorted design, the 3-link de Dion rear suspension is shared by both the North American and European Mitsubishi electric vehicles and has been modified slightly for the U.S.-spec car to accept wider tread tires.

Specially-designed Low Rolling Resistance Tires
Every 2012 Mitsubishi i sold in North America is equipped with a specially-designed set of low rolling resistance tires that feature a unique tread pattern. Manufactured by Dunlop Tires, the vehicle has been fitted with Enesave 01A/S- 145/65R15 in front and 175/60R15 in the rear. These tires have been developed exclusively for 2012 Mitsubishi i in the United States and Canada.

Electric Power Steering (EPS) System
Many Electric Power Steering systems featured on the vehicles of other auto manufacturers tend to offer less steering feel and road feedback to the driver in a best case scenario and sometimes feel artificial or even awkward at their worst when compared to a "conventional" (hydraulic) steering system.

That's why Mitsubishi engineers have spent a great deal of time and effort in developing a pinion-driven Electric Power Steering (EPS) system that is complemented by technologically-advanced EPS+ software that communicates well with the driver, enabling a natural and nimble degree of steering feel whether making a tight cornering maneuver at low speed or negotiating a sweeping bend at a faster pace.

Vehicle Stability and Handling – a Mitsubishi i Strong Suit
Thanks to its low center of gravity as a result of its main drive lithium-ion battery pack and major components including the electric motor, transmission and inverter being strategically placed down low within the vehicle, as well as a design that pushes the four wheels out to the far corners, the 2012 Mitsubishi i offers an excellent degree of vehicle composure and surprisingly athletic handling. And as the following chart demonstrates, the Mitsubishi i electric vehicle produces less body roll movement than that experienced by the gasoline-powered version of the vehicle:

Electric Powertrain = Greatly Reduced Vibration and Noise Levels
In addition to the high level of torque available at any time from the electric motor, there is another key attribute inherent with an advanced all-electric powertrain like the Mitsubishi innovative Electric Vehicle (MiEV) technology that powers the 2012 Mitsubishi i - whisper-quiet operation and dramatically reduced levels of vibration.

From the essentially silent running of the electric motor – the low level of noise especially noticeable when moving from a standstill - to the vibration-free "shiftless" single-speed transmission whether the vehicle is speeding up, slowing down or traveling at a constant speed, a greatly reduced amount of noise, vibration and harshness (NVH) ever enter the cabin.
This allows the vehicle's occupants to experience ride quality of exceptional aplomb.

Like a gasoline-electric hybrid, the motor of Mitsubishi's electric vehicle shuts down when the vehicle comes to a complete stop at an intersection or traffic signal. Since there is no engine idling as is the case with a car powered by a conventional internal combustion engine, the 2012 Mitsubishi i displays an extremely low level of vibration felt through the floor or the steering wheel when it comes to a standstill, as the following chart demonstrates:

Motor Mounting System

Designed specifically for the 2012 Mitsubishi i, the mounting system for the electric motor makes a significant contribution in the reduction of unwanted noise, vibration and harshness (NVH).

The front of the motor mount (located in the rear of the vehicle) features a pair of dual insulators that have been developed by Mitsubishi engineers for optimal minimization of vibration where the mount connects to the chassis by cutting off high-frequency noise produced by the electric motor.

The rear motor mount accomplishes the identical goals (noise and vibration reduction) as the front mount but is smaller and features a single insulator due to packaging requirements.

Both the front member and rear member motor mounting brackets are of a high structural rigidity yet light in weight.

Electric Vehicle Braking System
When developing the braking system for Mitsubishi's breakthrough electric vehicle, engineers paid particular attention to making sure that the system would offer the driver very good braking feel rather than an odd and artificial sensation through the brake pedal, the sort that is often experienced when applying the brakes on other 100% electric-powered vehicles. This has been achieved by countless hours of testing and tweaking of the regenerative braking system and by also incorporating a specially-designed electric vacuum pump that acts as a power source for the brake booster.

The very effective Brake Assist (BA) and Active Stability Control (ASC) systems are standard equipment on all units sold in the United States and Canada.

The Brake Booster with Integrated Brake Assist Mechanism

Unique to the braking system’s design is that this brake assist mechanism is integrated directly into the brake booster. This greatly enhances vehicle safety in panic braking situations because, when the system detects that the driver is depressing the brake pedal in a quick and abrupt manner, the brake booster and the brake assist mechanism reach full power instantaneously without the additional force required from the driver's foot as is the case with a conventional hydraulic braking system.

The braking system equipped on the North American-spec 2012 Mitsubishi i is identical to the setup found on both the Japanese and European-spec models.

Brake Electric Vacuum Pump
Another distinctive design element to the braking system of the Mitsubishi i is an electric brake vacuum pump as the power source of the vacuum brake booster that takes the place of the design common in internal combustion engine powered vehicles - one that relies on intake manifold vacuum pressure to power a brake booster.

Of note, the electric brake vacuum pump does not operate full-time but activates on-demand when necessary. This highly efficient system helps to reduce extraneous electricity consumption.

The electric brake vacuum pump is attached to a bracket that makes use of a dual isolation structure that helps to decrease pumping vibration from entering the cabin. Additionally, noise produced by the pump itself has been lessened by the design of its intake and venting structures.

Brake Vacuum Pressure System

The Brake Vacuum Pressure System is constructed of the following main components:

• Electric brake vacuum pump
• The vehicle’s MiEV Operating System  (EV- ECU)
• Vacuum sensor
• Relay
• Brake warning lamp (instrument display)/brake audible warning buzzer

System Operation
The vacuum sensor measures the vacuum pressure in the brake booster. The MiEV operating system EV-ECU receives this information and controls the electric brake vacuum pump accordingly. If this system fails or it detects a brake vacuum pressure shortage, this will automatically illuminate a brake warning light on the instrument display and an audible brake warning buzzer will sound to alert the driver.

Depressing the brake pedal repeatedly may activate the brake warning system (audible alert and illuminated warning light). If the system determines that everything is normal with the brake vacuum pressure, then the buzzer stops sounding and the warning light will deactivate after a few seconds, signaling to the driver that the vehicle is perfectly okay and that they may resume normal driving.

Of note, when the vehicle is initially started or when the brake pedal is depressed, the activation of the electric brake vacuum pump may be heard. This is perfectly normal and does not signal any malfunction of the system.

Environmentally-Friendly Mitsubishi i Components
In addition to being a significantly more sustainable form of personal transportation that greatly reduces the consumption of fossil fuels and the amount of harmful emissions, the 2012 Mitsubishi i incorporates numerous parts utilizing environmentally-friendly materials and/or manufacturing processes:

Manufactured from Recycled Materials:
Cargo floor pad and floor carpet (from plastic bottles), sound insulating/absorbing materials found in the dash panel and roof (from cotton cloth or linen bags).

Manufactured from Recycled Materials collected from Mitsubishi’s own factory:
Instrument panel, door trim and bumper sections (plastic remnants collected at the plant)

Reduction of Hazardous Lead-Based Components:

• Wheel weights made from iron
• Additives for wiring harness changed to barium, magnesium and zinc series
• Electrodeposition coatings (paint/metal finishes) changed to lead-free additives
• Additives for glass for ceramics changed to bismuth and zinc series