OK, you will get 600m if you do this: have the best rocket and best wheels, time your jump into the cart perfect (the bar goes ALL red), time your jump off the ramp perfectly (bar goes ALL red), and you keep the rocket parallel to the ground, don't face it down and fly too high in the sky. Please c & p this so it doesn't get lost.
It's an alright game, but the pyhsics suck, when you are drifting basically backwards, why would the car travel FASTER in that direction when you accelerate?! Drift is hard to control