some ideas

Great Game you designed here. Both entertaining, and intelligent. there is some things coming to my mind when playing the game. 

First: i think the possiblity too fill the empty spaces between the "bricks" would be good. 

Second, a "Free Roam" map would be awesome, where you can create whatever idea of a car you got, and then test the s*** out of it! 

Third: maybe you could have the choice of delaying some of your rockets, which could give the oppertunity to make a vehicle that first hover up in the air, and then second some rockets will launch it away! if you know what i mean?

Fourth: the Replay, i personally think the camera needs more zooming, (mostly out) because you can't go really far out, and sometimes i'm missing something. and also more slowmotion would do the trick, i want to see my vehicle crash into another vehicle, and see everything getting torn apart slowly.

Anyways, i look forward to the Beta and of course the full game.