It's one of those questions you've probably never thought to ask, but the second you hear it, it's stuck in your head. Automakers have produced cars with three, four, five, six, eight, 10, 12, and 16 ...

In a world of four-, six-, and eight-cylinder engines, the number seven sticks out like an awkward middle child. It may be a lucky number in Vegas, but it's practically taboo in engine bays. Not ...

Well, it turns out the humble number seven just doesn’t play nice with the laws of physics – or with accountants. One problem noted by Auto Motor under Sport in a recent article is that the crank ...