by “w is up, s is down” do you mean, w will always make the car go up the screen, s will always go down even if the car is turned around?
If the above, it may work in certain genres, e.g. the games where you typically play as a plane / space ship, dodging or killing things coming from the right, as you don’t really want an over complicated movement system for a fast paced game like that.
If your game is more like a 2D racing game, or a game where vehicles can help you move around the world, having a more accurate controlling for a car will feel better. (w is forward, s is reverse, a and d steer).
If you still want help deciding, tell us what the game is, and we can say what we feel would be the best.