If we're talking about Motorcycles, a modern motorcycle can stop quicker than a car. Most bikes have at least 280mm discs (same as most cars), most sports bikes have 290+ (normally 308-312mm) with 4 pot radially mounted calipers.
A bicycle on the other hand would not stop as good as a car unless, like what deserves to happen to most bikeists, they crash into a lamp post.