New York

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.