Motorcycles.

Have to be the most efficient means (with an IC engine, etc.) on land. (Not how muvh Bigger were all those roads and mews and alleys in UK, back when alot of their population rode solo, then added a sidecar when the kiddies came. Also their Petrol Bills.

Pity we have yet to see the Real, Useable, Air-Motorcycle (aside from the factor of too many people incompetent to drive such a thing..) And yes, I've seen several snazzy proposals through the years; was once interested in a Benson Gyrocopter (til I read the crash stats and noted the vulnerability of Those rotors.)

But in Principle - Air-cycle could Do It. In nice weather. :-)