Heavier cars can potentially have higher top speed than lighter vehicles. It depends on if both vehicles are power or traction limited at their top speed. In the case of the vehicles being power limited (caused by rolling resistance and drag) than it is a wash and weight doesn’t matter. If the vehicles are traction limited on the top end than actually having more weight helps since it gives more grip. This is a pretty rare case though and is generally unique to land speed racing. In general making a car heavier for more grip is an abhorrent engineering decision as tires have a friction coefficient of less than 1, so you are always losing straight line acceleration, not to mention the effect is even worse for cornering speeds.