they need to carry the heavy gas engine around even when isn’t needed and to adds overall weight of the vehicle and burden the performance of the electric motors.
What about the idea of removing the gasoline engine when you’re shore you won’t need it? This kind of concept is already a fact. A Romanian team comprising of a designer, an engineer and an automotive journalist have created a minicar concept called the SCIhyMod that would allow you to do it. The vehicle is just a concept though that offers a new perspective to green car manufacturers to get more efficient solutions.
This engine removing is possible due to a “logistic center” at the rear and the transformable vehicle allows users to swap the gasoline engine module that powers the rear wheels for a battery pack that fuels the electric motors powering the front wheels.
The range extender used in the vehicle is something similar to the ones found on popular production models like the Chevy Volt and the Fisker Karma.