Estimated Price: £25,000 - £30,000

Following the success of the Porsche developed RS2, Audi returned to the seriously fast estate car formula in 1999 with the B5 RS4, although this time the project was very much an Audi and Cosworth affair. Starting with the S4's 2.7-litre twin-turbocharged V6, Cosworth Technology extensively reworked the engine with revised cylinder heads, larger turbochargers and numerous internal changes, resulting in 375bhp and 325lb/ft of torque. Drive was sent through a 6-speed manual gearbox to Audi's Quattro four-wheel drive system, launching the RS4 from 0-62mph in just 4.9 seconds and onwards to an electronically limited 155mph.

Unlike its B7 successor, there was no Saloon or Cabriolet option. The B5 RS4 was available exclusively as an Avant, and visually it was anything but an ordinary A4 estate. Huge flared wheelarches accommodated its wider track, complemented by deeper bumpers, enlarged air intakes, sill extensions and 18-inch alloy wheels. More than 25 years later, its proportions remain arguably amongst the finest of any fast estate and a real symbol of when car manufacturers threw the rulebook out the window and went a little bit mad.

B5 AOA is a particularly lovely example, finished in Avus Silver Metallic over black leather and showing just 68,520 miles from new in the hands of four owners. The interior remains wonderfully representative of Audi, with carbon fibre trim, sporty yet supportive Recaro heated and electrically adjustable front seats, an electric tilt and slide sunroof and upgraded Bose sound system.

The car was acquired for its current owner in 2020 and forms part of the same collection as its B7 RS4 younger sister, also offered within the sale. Since then, it has lived in specialist storage with Audi marque specialists APS of Brackley, who have also been responsible for its maintenance throughout our vendor's ownership.

Much like its sibling, a small number of carefully considered upgrades have been made with usability firmly in mind. The original cat back exhaust has been replaced with a Milltek system, whilst braking performance benefits from a B7 front brake conversion. The suspension has also been upgraded to highly regarded KW Variant 3 adjustable coil-overs, mirroring the set up fitted to the B7 and providing a quality modern replacement beneath the car.

Importantly, the RS4 is accompanied by a full and comprehensively documented service history, together with its books, two keys, receipts and previous MOT Certificates. Prior to passing to its next custodian, APS will carry out a service and fresh MOT, ensuring it's ready to be enjoyed. The wonderfully appropriate Cherished Registration, B5 AOA, is also included in the sale.

Today, with 375bhp perhaps no longer sounding outrageous on paper, it is easy to forget quite how serious the B5 RS4 was when new. More importantly, its performance is delivered without the layers of technology that characterise its modern equivalents. With just 68,520 miles, four owners and long-term specialist care, B5 AOA represents a superb example of where the RS4 story really began.

Offered alongside its B7 sister car, the pair provide a fascinating demonstration of two very different approaches to the same brief. One uses a howling naturally aspirated V8, the other a Cosworth developed twin-turbo V6, but both combine a manual gearbox, Quattro four-wheel drive, muscular styling and a genuinely useful boot. We can't think of many better two-car garages.