From Chapter 2 of the “Transportation Energy Databook” from the US department of Energy (with slight format changes). The Commercial air numbers maybe high do to freeloading cargo.
Thousand BTU/Passenger Mile 4.2 Public Transit Buses 3.9 Personal trucks 3.4 Cars 3.3 Commercial Air 3.0 Rail - commuter 2.8 Rail - transit 2.6 Rail - intercity 2.2 Motorcylces
My motorcycle/scooter riding friends may continue to gloat. And no this is not an excuse to to drive rather than take the bus, since adding you to a bus costs about zero btu/mile; and of course motorcyclists who ride in packs should get a car.