Ford Escort RS CosworthThe Ford Escort was a pretty common car in the U.K. Over 4.1 million were sold during its 33-year production run, and a good number of those are still around. But not every edition was quite so common, and one of the rarest Escorts — the Ford Escort RS Cosworth — is very difficult to get a hold of. Only around 7,000 were made, and many of those ended up hurling sideways into a ditch when their drivers got a little too confident.This particular "Cossy" was the natural follow-up to the exciting and breathtakingly popular Ford Sierra Cosworth. Like its predecessor, the Escort RS Cosworth was built for competition, though it was geared more towards rallying than stock car racing. It found success in the WRC between 1993 and 1998 — helping Ford break through in the sport, with victories at the likes of the Monte Carlo rally, Tour de Corse, and Acropolis Rally.It shared a chassis with the Sierra, but had a number of key upgrades — including all-wheel drive as standard. It is capable of going from 0-60 in 6.1 seconds, which is still more than decent for a gas-powered hatchback by today's standards. If you keep your foot down for a while, it will cap out at 140 mph for top speed. The Ford Escort RS Cosworth was eventually replaced with the Ford Focus, both on the road and on the rally stage, but the Focus was never as cool.Audi S4 PlusAudi had a strange start to the 1990s. The A4 was launched on the Audi 100 platform, which it would later share with the A6. The two wouldn't become truly distinct vehicles until 1997. The Audi S4 launched in 1991 and was, as it still is, a souped-up performance version of the A4 Sedan — coming in either a "Saloon" or "Avant" body style. However, there was an even higher power variant around for a short amount of time. The Audi S4 Plus really stood out in the engine department. Gone was the inline-five engine the "standard" A4 and S4 were packing. Instead, the S4 Plus came with a hefty 32-valve, 4.2-liter V8 capable of belting out a respectable 276 horsepower. This all went through a six-speed manual transmission, and Audi's "Quattro" all-wheel-drive system also came as standard. The S4 Plus, although rare, proved popular — even F1 legend Ayrton Senna had one in silver. If you want to mimic the Brazilian F1 hero, you may have a hard time. An old S4 isn't too difficult to find, but the S4 Plus is a weird, yet potent, piece of automotive history. Cool for a few years, and then gone.