But there were sound technical reasons for using the car as well. Its air-cooled engine was mounted in the rear, making it fairly simple to swap out the flat-six for a 115-horsepower AC induction motor. The conversion to electric drive added close to a thousand pounds to the curb weight, primarily from the addition of a 532-volt, silver-oxide battery array. It was housed up front, in the Corvair sedan's spacious "trunk," giving the Electrovair II a range of 40-80 miles.
GM claimed a top speed of 80 miles per hour, and a 0-60 mph time of 16 seconds. While that seems slow, performance was actually similar to the standard production Corvair.
The problems GM faced with the Electrovair were the same ones that always bedevil electric car programs. Range was limited, because there was only so much room for batteries in the Corvair. Expensive silver-oxide batteries were chosen because of their high energy density, but they were still heavy and they wore out after being recharged just 100 times.
GM never planned for the Electrovair to become a real production model. But that didn't stop it from showing the car and providing test-drives to awestruck journalists who then predicted that electric cars were the wave of the future. But they weren't. As the '60s turned into the '70s and the first regulations for automobile emissions were created, GM's engineering might was focused on more practical concerns, like developing the catalytic converter for gasoline-engine cars. It would be two more decades before growing environmental concerns gave GM reason to develop the EV1, the first electric car that was more than a glorified science fair project.