Wow! Just amazing :). I really love the idea of turning only one direction! The game is quite difficult but I think that makes it even more interesting. There is only one thing that spoils the experience a little bit - the pieces that fall on the ground turn you in completely random direction - I think I would make it more deteministic - or 180 degrees or maybe full stop. :)
The graphics is just amazing - I really admire the idea of the 'inside a car view'. This is just briliant! :)