One of BMW's most popular cars just turned 30 - here's why it was so great

Most often for marketing purposes, many car companies today like to compare their road cars to racing cars.

Somehow, they argue, their exploits on the track are embedded into their production cars.

But really, they're lying - road cars have little to do with their racing cousins. And for good reason: race cars are uncomfortable, angry, and while they may do well toward their intended goal, they are quite terrible at just about everything else.

But in 1985 BMW really would sell you a race car. It was called the M3...and it was awesome.

Why would BMW choose to do such a thing? It all comes down to one word: homologation.

Roughly, those five syllables mean "approval by an official authority." In motorsport, it has to do with the rules of many racing series, which often require that competitors' cars have a certain amount in common with actual production cars.

The rules also often require that the company sell a specified amount of those cars to the general public. But because high performance versions of cars are expensive to produce, companies often build no more than they have to.

And in the 1980's - an era of intense competition in international motorsport - BMW really had to find something better than the base 3-series.

Because it really wanted to win.