Nice concept!
Never thought that slay the spire type games could be implemented on a more real time action game.
In my opinion, constant speed may make the game smoother, so that it doesn't get either too bogged down or in hyper speed, which forces the player to wait it through. I think speeding up through the course of time may be nice.
Really liked the car-type-changing mechanism, it forces player to make decisions on dodging or ramming the people.