Little tip for getting "PayDay" launches: turn the quality to high for the launch and it slows down the needle a bit. Then you can turn the quality down to low and make the game move faster when the boss is in flight.
Very hard to balance while in the air. It spins way too easily and is very hard to land while keeping momentum going forward. The nitro also should stop when I release the x key. It also seems like this is a rehashing of cyclomaniacs except with cars.
Too short and it would be nice to know that some of the environment was movable before starting the game. Great concept though, just wish there were more levels.
The only idea that I would add would be to ensure that the further you got into the game, the better equipment you find on enemies. I've been finding quite a bit of basic-level equipment throughout the last stages of the game.