I'll go ahead and bump this and also try my hand in the competitions again.
58330 and round 6 after a couple initial tries.
I usually just jump right into games so it took me a few tries to figure things out:
You can tap button 1 to lay down some kind of cloud that blocks the red cars. Don't use it too much though, it drains fuel.
Once you get the "S" flag, the remaining flags will each have double their original point value. It goes without saying that you should seek this flag first, especially in the early easy rounds.
And of course, the more fuel you have at the end, the more points you get.
I got through 5 rounds without losing a life then tanked them all in round 6. I should be able to nab a better score.
Good luck, everyone!