Electric cars promise to change the way we drive, making it greener and potentially even safer. But electric vehicles' path to wider adoption is full of hurdles.

Electric vehicles may be the future of the auto industry. And if they are, that may spell the end of many traditional auto jobs.

The problem for the workers is clear: The electric motors that will power those new vehicles have far fewer moving parts than traditional internal combustion engines and the transmissions that go with them.

Building a traditional powertrain is the most labor-intensive part of building a car. Building an electric car requires about 30% less labor than building a traditional gasoline-powered car with its engine, fuel system, transmission, and other complex parts, according to estimates from Ford (F) and other industry experts.

“The internal combustion engine and transmission are vital parts of automotive manufacturing,” said Brett Smith, director of research at the Center for Automotive Research, a Michigan think tank. “They are ones that are clearly at risk right now. That has everyone concerned.”

The traditional gasoline engine has carefully engineered pistons and fuel-injection systems that differentiate one vehicle’s performance from another. It also needs a complex transmission to transfer power to the wheels with a series of gears.

An electric motor needs none of that and works with a fixed, single-gear gearbox that powers the wheels.