Driverless Cars Are Giving Engineers a Fuel Economy Headache

Judging from General Motors Co.’s test cars and Elon Musk’s predictions, the world is headed toward a future that’s both driverless and all-electric. In reality, autonomy and battery power could end up being at odds.

That’s because self-driving technology is a huge power drain. Some of today’s prototypes for fully autonomous systems consume two to four kilowatts of electricity — the equivalent of having 50 to 100 laptops continuously running in the trunk, according to BorgWarner Inc. The supplier of vehicle propulsion systems expects the first autonomous cars — likely robotaxis that are constantly on the road — will be too energy-hungry to run on battery power alone.