There's a common misconception that FWD cars don't need spoilers. That assumption is false. Even though it's dragging the rear end (as opposed to RWD pushing the front end), wings still can aid in keeping the rear of the car compliant with the road. At higher speeds (100+), wings can also alleviate pressure behind the car, decreasing drag and making the car more aerodynamically slippery. If you have any questions, have a look at the British Touring Car Series.