Once marketing decides what type of vehicle or product to produce variants can now be discussed.

A variant can be anything really. We will take a compact car. The variants can be a 3 door, 4 door, 5 door version of the car. Also trim levels as well as powertrain variations. On the product side we can do the same basic thing. Start with a concept like a standard grip on a cordless drill. We can change it to have a gel over mold on the grip. Or change the type of drill completely by having a clutch put on or making it a hammer drill etc...

The reason behind this is to maximize the potential of the item being created. The initial design process is the most time consuming and expensive. By adding variants you increase the market size or enter in to different segments for less time and money. What I am saying is, you have the wheel. Just make it better in this case. Do not try and make a whole new one.