Homologation. It's the racing rule that results in some of the world's greatest road cars. To race, many cars have to be homologated, which means they have to have a number of street-legal counterparts to prove they're part of a brand's production line. Sitting high on this list of all-time homologated greats is the Porsche 911 GT1 Evo, and this is the story of how that car came to be.

In the mid 1990s, the FIA created a new racing class called the BPR Global GT Series. The goal was to pit supercars against one another after they'd been crafted into true racing machines. However, for an automaker to compete it would have to hit a homologation target. That means a road-going version of the race car would be built and sold to the public. Any time a race series has a homologation requirement, the resulting production cars are always stupendous.

Porsche had its eye on the GT1 class. There it would compete against the likes of the McLaren F1 and Ferrari F40. Porsche's engineers drafted an entirely new version of the 911 and called it the 911 GT1. This was unlike any 911 ever produced as the engine sat in the middle of the car instead of at the rear. That engine was a twin-turbocharged 3.2-liter flat-6 that spun out 592 horsepower. Wrapped around that engine was a stretched out version of the 911 bodywork.

The 911 GT1 arrived for 1996 and Porsche launched an upgraded version for 1997. Called the GT1 Evo, the second-year car utilized the same powerplant but was given aero tweaks front and rear. In fact, it previewed the headlights that would wind up on the then-upcoming 996-generation 911. It could accelerate quicker and corner better. The GT1 Evo was clocked at 202 mph on the Mulsanne Straight at Le Mans.

The best of the bunch, however, is the car known as the Straßenversion. That would be the Street Version of the GT1 Evo race car. Fitted with a slightly detuned version of the race motor, the road car was rated at 536 horsepower. That was good enough to take it from 0-62 mph in a mere 3.9 seconds. Just 21 units were ever built, despite the fact that homologation requirements asked for 25 cars. Another car was recently converted to a street car from one of the race cars.

The 911 GT1 Evo is one of the greatest 911 road cars ever built. And for that we owe a tip of the hat to the wonderful term that is homologation.