Probably an aerodynamic gyro-train running a combined cycle powerplant: high-compression, turbocharged/turbocompounded diesel powering a steam turbine via waste heat. Vacuum sealed gyroscope on superfluid bearings...superconductors used throughout with ultra high efficiency motors/ultracapacitors for the traction drive system.
Gyro-Train
If you meant personal transportation, I'd suspect a faired motorcycle (a la Craig Vetter) would be your best bet.
- LostCause