It is a cool concept. I like everything it brings to the table, the car, the course and the timer to keep it difficult. Only negative was the one hit kill in my opinion. I would understand the electricity being a one hit kill but in my opinion you should be able to hit the wall maybe 3 times or so, and decrease that number through the levels. I am not a designer so I don't know how diffucult things may be so my ideas are soley from a gamer perspective.
This isn't a racing game and the car is too sensitive. Even a light tap to a wall causes the car to blow up and the level restarted. This is an interesting take on tower defense, but the car being destroyed in one hit ruins it for me.
I like the idea, but I think the game is too difficult. The steering is too sensitive, esp. since you fail when hitting the walls. If you had something like health points or at least better controls over the car, this would be way better. Also, since you use keyboard controls, it would be very good to have a key for pressing Continue instead of having to grab the mouse again.