Does a car go faster if it was lower to the ground?

That needn't always be. Faster cars are built lower to the ground. This is primarily to lower the center of gravity of the car. If the car is much higher above the ground, it's center of gravity would also be higher and that means the car would have lesser stability. Fast cars have to be stable even at high speeds and a slight nudge would be enough to throw the car off-balance if the ground clearance is high. Hence as a safety measure, fast and super cars are built lower to the ground.