well, my friend argues that speed is not directly related to power of the car. There are several other reasons that effect the speed. I don't know what to say, I think he's wrong. He owns an accord by the way.
I would say that your friend is right. Engine sure plays a powerful role in the speed, but there are other reasons like the weight of the car, suspensions, tires.
Speed isn't directly related to power. There are many really powerful cars on the road (quite a few muscle as well), that are not known for their speed.