One of the coolest Audis ever wasn't actually built by four-ring brand. The Audi RS2 Avant (also known as the Audi 80 RS2) was built from 1994 to 1995 in a joint venture between Audi and Porsche. Audi has celebrated this car as the starting point for its now-famous lineup of all-wheel-drive performance cars, such as the new RS6 Avant, even creating a limited edition to pay homage to the RS2. The RS6 shares its 4.0-liter V8 engine with Porsche, but the RS2's Porsche connection went significantly deeper.

Porsche played a major role in developing the RS2, so it decided to invite the car back to its headquarters in Zuffenhausen for a commemorative video. There are very few records documenting the RS2's creation, but Michael Holscher, head of the RS2 project at Porsche, and Ralf Friese, a corporate historian at Audi, give their accounts of how this amazing car came to be.

Under the hood, the RS2 uses a unique 2.2-liter turbocharged five-cylinder engine, throwing down 311 horsepower and 302 lb-ft of torque to all four wheels through a six-speed manual transmission. Though it's nearly half the power found in a modern-day RS6, the RS2 was the quickest wagon in the world when it debuted in 1994. The car could hit 30 mph in only 1.5 seconds (quicker than a McLaren F1), 62 mph in 4.8 seconds, and go on to hit 163 mph.

"Right from the start, the aim was to integrate technology, styling, and elements from Porsche into this car," said Holscher. The RS2 features Porsche wheels and red brake calipers, exterior mirrors, and engraving on the engine that reads, "Powered by Porsche."

Audi only produced 2,891 RS2 examples, making them extremely rare today. For Audi and Porsche fans alike, this is a unique car that will likely spike in value beyond current prices. You can currently pick up a nice RS2 for under $70,000, but we have a feeling these prices will seem laughable in a few years. It may not have a Porsche badge up front, but the RS2 would likely be welcomed at any local Porsche car show. Their rarity and connection should make them highly sought after.