Why Are Motorcycle Top Speeds Slower Than Cars? It has nothing to do with the Motorcycle itself, but rather the human on top. Something Drivers take for granted, is that as long as they aren't super heavy, their height or general shape, won't affect the vehicle they're driving. However, your choice of HELMET can literally change your Top Speed and Acceleration on a Motorcycle, as well as your choice of clothing, gear, and yes, your size. Motorcycles don't discriminate and neither does the pavement if you fall. Riding isn't for everyone, so stay in shape, and don't be a wuss, then swing a leg over two wheels and feel more connected to the road than any Manual Transmission Car, will ever "Engage" you.