Ok, I am not going to give a cheerful review for this...
1. I hate games with bad physics and this game hasn't seen any physics at all. For example: according to what physics law when a car is 4 wheels on the ground with engine turned on to move forward it is moving backwards???
2. That bouncing is just ridiculous, on everything...
3. Even the jump is just a simple bounce not helping sometimes in any way.
4. On the higher levels: are the opponents invulnerable to all obstacles?
5. The place on the grid should depend on the total amount of stars earned between 3 last levels, not be just 0-1: up one place or not;
6. More about the opponents: it seems that the jump/boost limits do not apply to them since they can just fly almost all the time - I like challenging games, but the ones that are fair to the player.