RPM

Thank you Joe.
The car is lowered on a sports suspension and has an original Honda front spoiler which might help aerodynamics a tiny little bit. On the other hand, it has mud-flaps and is rolling on ultra-sticky high rolling resistance Goodyear F1 tires (~40 psi), so I think it's overall worse than stock in what FE is concerned.

For me, it's all about driving technique really.

what have you done to that car to get that kind of mileage? wow!