Nice Entry!
Overall I really like the idea of the round based power ups makes you defiantly feel strong round after round. I really enjoyed your rewind mechanic and thought the execution on it was really well done in terms of the effects.
I would like to see a slight reduction to the speed, found it quite hard to drive for sure. I think the rewind mechanic as well instead of hold could just be a tap that returns you a set distance back, I found a lot of times I wasnt holding it down long enough. The last same tweak would be the UI for the cooldowns, I believe them being in the bottom left and that size was quite hard to glance to while playing the game. An implementation similar to games like LoL might work in helping that out.