Everything You Need To Know About Buying A B7 Audi RS4

Today, well into the 2020s, the idea of 400bhp-plus barely raises an eyebrow. But when Audi revealed the B7-generation RS4 back in 2005, its headline figure of 414bhp sent eyebrows soaring.

The engine was very much the star – a 4.2-litre, naturally aspirated V8, hewn entirely from aluminium and with a redline at 8250rpm. But the context was important too – until now, this was the Audi A4, an executive saloon like your dad drove. Or, soon afterwards, a convertible like your dad drove after the divorce. Or – perhaps the coolest of the lot – an Avant estate like you were taken to school in.

Except, of course, it wasn’t really. Sure, the bodyshell was the same, but the RS4 had upgrades aplenty over the standard A4. Quattro all-wheel drive was standard, with 60 per cent of the power sent to the back wheels from the off. That stood it apart from its chief rivals – the E90-series BMW M3 and the Mercedes-Benz C63 AMG, which stood by their rear-wheel drive traditions.

The RS4’s handling was enhanced dramatically through a system called Dynamic Ride Control. This wasn’t a computer-driven bit of tech to control individual dampers, like you’d get today; instead, it was a hydraulic setup that used valves to connect diagonally opposite dampers and transfer fluid between them depending on what forces were detected at each wheel. It gave rather staid A4 a shot of something serious through the corners.

The first RS4 to appear was the saloon model, available in a single trim with the option of a Technology Pack, featuring sat nav and a six-CD autochanger. You could also spec five-spoke 18-inch alloys instead of the standard 19s, and Sports Suspension Plus – a firmer setup that sat 10mm lower than standard. Electric Recaro seats were also available from the options list, as well as a range of interior upholstery choices and other luxurious extras.

No sooner had everyone raved about the new car, Audi launched the Cabriolet and Avant estate models, which arrived in the UK in the summer of 2006, giving buyers the option of fresh air to go with their scintillating performance, or the excuse that “it’s a practical family car” when explaining their purchase. The Cabriolet isn’t as taut to drive, however, and can suffer from scuttle shake due to the body flexing.

If you’re hankering for an RS4, here are a few things to keep an eye out for.

What to look for

Service History

This goes for any used car you’re after, but on the B7 Audi RS4 a comprehensive service history and evidence of preventative maintenance can save you a fortune down the line. It shows that past owners have been attentive to the car and given it all it needs.

Engine and exhaust

The engine of the B7 Audi RS4 borders on a piece of art, but if it hasn’t been stretched on a regular basis carbon can build up. This can be signified by blue smoke from the exhaust, caused by oil gathering in the intake manifold. A rough idle can also result, and a drop in power. A blast at high revs can potentially help, but if it’s bad you’ll need to have the manifold manually cleaned – something some owners say you should do every 40,000 miles or so. It’s not cheap or quick, though.

Many owners have reported issues with the flaps installed on the intake manifold, which open up at higher revs and are designed to optimise air flow into the engine. However, the screws holding these can fail and get ingested into the engine, which can cause horrendous damage. For that reason, many owners simply delete the flaps. It’s worth finding out whether this has been done on a car you’re looking at. If it hasn’t, have the condition of the flaps checked out.

Watch out for misfires – this is often caused by coil pack failure, and if it’s not sorted then unburned fuel can knacker the catalysts. You should see an engine warning light on the dash if this happens, but best to listen for misfires too.

The exhaust system has vacuum-operated bypass valves that are activated when you select Sport mode. The actuators for these can seize, so listen for a change of exhaust note to make sure they’re working. Some owners just delete them.

The RS4 can go through oil pretty quickly. Around a litre every 1500 is common, but if it’s drinking a litre in less than 1000 miles, that could be a sign that the PCV (positive crankcase ventilation) valve has got clogged or damaged and needs replacing.

Suspension

The Dynamic Ride Control suspension system is an integral part of the car’s character, but because it’s hydraulic it can be prone to leaks. And be warned, fixing it can be pricey. A knocking noise can indicate that the system’s main valve has failed, and look too for leaky dampers. Keep in mind that if one’s gone, you should also replace the damper on the diagonally opposite side, and on the same axle. Which basically means if one goes, you’ll have to replace the lot, which requires specialist equipment to fit. The system will then need repressurising, too.

Because of this, lots of RS4 owners just ditch the DRC system altogether and fit coilovers, although that comes at the expense of the RS4’s factory character. If you want originality, check to see what’s been done.

Check the upper control arm bushings as they can wear out, signified by a clunking noise when on full lock.

Bodywork

The bodywork and electrics are generally pretty bulletproof, so any issues could be from accident damage. The bonnet and front wings are aluminium, so rust isn’t an issue there. That said, the aluminium mirror mounts can oxidise. While you can fix it by powder coating them, it may well be easier to just replace them. They’re not cheap, however.

In the Avant models, watch out for water in the boot, which is a sign that the boot lid seals have failed and will be moderately pricey – a few hundred quid – to replace.

Brakes

The RS4 came with massive eight-piston Brembo brakes and 365mm front discs as standard. They’ll almost definitely have been changed by now, but beware of OE discs. They were prone to warping and subsequent vibration caused by the holes filling with brake dust, which means they couldn’t get rid of the heat under braking. You can get the discs skimmed, or replace them with slotted units that won’t warp. Many owners have changed the brake setup completely – this isn’t necessarily a problem, as long as it’s been done properly.

Tyres

The RS4 was originally shod with Pirelli P-Zeros, but other high-performance tyres work well, too, with Michelin Pilot Sports particularly favoured by lots of owners. If the tyre pressure monitoring system isn’t working, you might need to replace the battery in the tyre valves as they only last for a few years.