Out of interest, why not a small car? Ok so the wheels have to come off but you can still fit 2 blokes and 2 bikes inside a small car, we did 4+4 in a 206!
The problem is anythign that isn't 'gutless' is expensive as theres no differece in the isurers eyes between you the extream sports dude who takes life in own hands, the kid down the road who does nothing more dangerous than chess, and the boy racer on the next street. And as a result you all pay the average premium, which is very high.
The problem is your likely to crash, and with a bigger car you'll do even more damage.