Back in the late 1990s, Volkswagen released an entirely new platform for their vehicles that gave them more usability than could be replicated until the PL71 platform shared by the Touareg, Cayenne, and Q7 large SUV.
When Volkswagen debuted the B5 platform, it featured a longitudinally mounted engine, an option for all-wheel-drive, and even initially offered a long-wheelbase variant. With the option for the all-wheel-drive system, Audi jumped at the chance for something new and unique.
The B5 Audi A4 and S4 debuted in the United States in 1999 after being available as the A4 prior. Fitted with a turbocharged V6 and manual six-speed gearbox, the S4 was a winning combination of a race car and family hauler from the showroom. Audi managed to do one of the most difficult things a manufacturer can do: making the first generation of a car be incredible compared to the ones afterward. So maybe it's time Audi went back to the A4/S4's roots and also, maybe throw in the manual gearbox again too.
From The Beginning
The B5 came from the factory with a plethora of options. With front-wheel drive, all-wheel drive, three different size engines, and even two body styles, the B5 platform offered Audi a unique platform to keep improving upon. The B5 S4 came standard with a twin-turbo 2.7-liter V6 engine mounted longitudinally, paired with a manual six-speed gearbox or ZF-sourced automatic five-speed. The water-cooled BorgWarner turbos brought the car to 250 horsepower, making it more powerful than the comparable C43 AMG at the time, as well as the E36 M3.
The B5 S4 offered versatility alongside its impressive performance figures. The B5 came as both a sedan and the Avant variant. The Avant offered dramatically more cargo space, coming to around 31 cubic feet with the rear seats up compared to the 13 cubic feet in the sedan. The B5 was seemingly a do-anything car. All-wheel-drive, tons of cargo space, manual gearbox, and more than enough power, the B5 S4 was a force to be reckoned with.
Tunability
The B5 was incredible in its own right, but that didn't stop the tuning community from making them absolute monsters. Although not necessarily "reliable", the cars could build massive power. According to one CarThrottle article, a modified S4 came up for sale back in 2015 for under $7,000 USD. The one in question was a track setup, so more focus was had on the suspension and steering, but the engine had been reworked slightly. While the seller said it is reliable, he did not list any maintenance history.
In a video from YouTuber Cvdzijden - Supercar Videos, a heavily modified B5 S4 sedan made an appearance. Putting out over 700 horsepower, the car was tapping around 166 miles per hour in the half-mile. With some turbo spool noises drowning out the car's exhaust even, the S4 (which sounds engine-swapped) was able to rocket down the strip faster than many of the supercars in attendance. Other examples of heavily modified B5 S4 have anti-lag systems and are more than capable of outperforming a number of modern performance cars as well.
At What Cost
As good as the B5 S4 was, it was not without fault. The car lacked crown gears and used now-outdated Torsen hardware. With age, the manual gearbox also was prone to slipping more and more. According to Super Street Magazine, "the B5 S4 requires a simple approach to maintenance—just spend all your time and money on it, and you'll be fine."
Regular maintenance, such as tires and oil changes should not be too costly, but that's where the relatively cheap maintenance ends. The turbos are prone to failure as the car ages but can be semi-maintained by letting the car properly warm-up and cool down every time you drive.
As cheap as some of these B5 have become, incorrect maintenance will easily set one back well over $5,000 for some repairs. Turbo replacement is costly, as is the timing belt and the water pump. Buying one with full maintenance done at higher mileage should still cost under $8,000 in some cases, but out of pocket costs of the belt and the water pump is around $8,000 on its own.
Should You Buy
In short, yes. The car is incredibly well-sorted and is capable of massive horsepower. With proper maintenance, they are amazing cars and truly a do-everything vehicle. In a DriveTribe article, one of their contributors bought one two years ago that had been meticulously maintained. When maintained properly and as immediately as possible (or even beforehand) these cars are insane performance "bargains". If Audi were to bring back the B5 S4 to any degree, it would be a hit in the automotive world. Maybe the current buyers would be unhappy since it would not be an electronics-filled box for transportation, but to enthusiasts, it would be a full return to form for the brand's performance division.
Sources: DriveTribe, SuperStreet, Audi Club North America, CarThrottle