Toyota Motor Corp. exhibited 1/X, a concept car whose weight is reduced to about 1/3 of that of Prius, at 40th Tokyo Motor Show 2007.
The weight reduction was achieved by the adoption of carbon fiber reinforced plastic (CFRP) for body frame. The interior space of the 1/X is the same as the Prius, the company said.
CFRP is used for the base frame of the vehicle body, namely, underbody (floor frame), B-pillar (column between the front and rear doors), A-pillar (column located on both sides of windshield) and part of the frame extending from the A-pillar to the rear side.
CFRP plates formed to have a wavy cross section are placed in the area on the underbody located under the front seat and behind the front and rear lights. They are provided as reinforcement to ensure safety in collision, the company said.
The reduced frame weight resulting from the adoption of CFRP enabled the vehicle to employ a smaller engine, lighter powertrain and narrower tires, thereby significantly reducing the total vehicle weight. Specifically, 1/X features a 500cc engine and weighs 420kg.
According to a demonstrator from Toyota, the lower limit of the weight is not 420kg and "it could have been even lighter." However, the most appropriate weight is about 420kg in order to provide a driving condition and acceleration performance that is stable irrespective that the driver is alone or the maximum number of passengers (four people) are in the car, the company said.
The engine is small enough to be mounted under the rear seat, which is usually dead space, without affecting the ease of getting in and out of the vehicle, the company said. When the engine is located under the rear seat, it does not take up the trunk or interior space.