https://www.cnet.com/roadshow/news/ford-university-of-michigan-flying-car-study/

In any case, the Ford and U of M study found that for shorter trips of 22 miles and under, a car -- especially an electric -- one would be more efficient in terms of energy consumption. This is mostly down to the fact that getting a vehicle airborne takes massive amounts of energy. While getting a car up to road speed isn't that big of a deal.

Over 22 miles, though, and the aircraft starts to pull ahead. This is because once in the air, maintaining a cruising speed isn't especially taxing. Aircraft are, by their very nature designed to slip through the air with minimal resistance, so the motors aren't having to work very hard to maintain speed.