Moller is hardly the first inventor bent on making flying cars a reality, but he’s likely the one person who’s been at it the longest…

Moller’s distaste for batteries in the new generation of flying cars makes him the outlier. A year ago, he stopped work on a hybrid model of the Skycar, opting for a version only with a rotary-powered engine.

“Even though the battery safety brings in some issues, the rest of the aspects in terms of the number critical points of failure and so on are a lot fewer,” says Shashank Sripad, a battery researcher at Carnegie Mellon University who recently co-authored an article on the promise of urban aircrafts. “I would say I’m very optimistic.” The top air-taxi contenders today, including the EHang 216, the A3 Vahana, Wisk’s Cora, and the Archer Maker, are all battery-powered.