After my first week of owning this car I only for 380kms to the tank. Now this doesn't sound right considering my previous car (R33) could run till about 400-420kms.

What could be causing this? Yes I've hit VTEC a few times since owning it, but surely it can't eat fuel as much as a turbo can it?

I'm thinking its more mechanical. Something isn't working the way it should be and possibly causing the car to work harder and therefore eat more fuel?