That's the evidence you're giving to dismiss the ability of flying cars to distribute over multiple altitude? Once we've accepted the hypothetical that technology allows for a single car to fly from A to B safely (which is almost certainly automated), it seems clear that having cars move at different altitude will be trivially possible.
> Also, with the advent of KERS and other regenerative systems cars will be able to recapture the bulk of energy consumed for elevation changes. To my knowledge there's no such effective system for planes. So the efficiency on cars is still higher than air vehicles.
No one is disputing that regular cars are more efficient than flying cars. But trucks are less efficient than container ships, and we still use the former when the latter is impossible or too slow. You said "Flying is not a valid commute solution and never will be because of physics", and this just isn't true.