Audi RS6 Avant (C8)

The fast estate benchmark

The C8 Audi RS6 Avant arrived in 2019 with a 4.0-litre twin-turbo V8, 591 bhp, 800 Nm of torque and an eight-speed tiptronic gearbox. It is the fastest RS6 yet, and it is also the most complex. Standard air suspension, a 48-volt mild-hybrid system and optional rear-wheel steering make it a very different car from the old C7.

The RS6 is a family estate that can keep up with a sports car. It has a huge boot, a comfortable back seat and a cabin that feels expensive. The V8 makes a wonderful noise, and the quattro system puts the power down in all weather. It is a car for someone who needs practicality but refuses to give up performance.

The problem is that the C8 is heavy and complicated. It is not as sharp as an M5 Touring or as involving as a Porsche Panamera Sport Turismo. It is also expensive to run, and some of its air suspension and electrical faults can be very costly. A used RS6 can be a bargain or a money pit, depending on how it has been maintained.

Running costs

Audi's service schedule for the RS6 is typically every 12 months or 10,000 miles, with longer intervals for some items. A minor service at an independent Audi specialist is £600 to £900. A major service with plugs, filters and fluids is £1,200 to £1,800. The 4.0 V8 uses a lot of oil, and the mild-hybrid system adds another layer of complexity.

Tyres are expensive. The RS6 runs 21-inch wheels as standard on many cars, and a set of premium tyres is £1,200 to £1,500. The optional 22-inch wheels look great but cost more and are more vulnerable to kerb damage. Brake discs and pads are £2,000 to £3,000 for the standard steel system. Carbon-ceramic brakes were optional and are very expensive to replace.

Fuel consumption is around 25 mpg on a motorway run and low 20s in town. The 48-volt system helps a little, but this is still a 591 bhp V8. Insurance and road tax are high. Budget for £2,000 to £3,000 a year in maintenance and consumables if you cover 10,000 miles, and more if you use the performance.

Air suspension and chassis

The C8 RS6 uses air suspension as standard, and it is one of the car's best features. It can raise for speed bumps, lower for motorway cruising and stiffen for cornering. It is also a common failure point. A car that sits unevenly, takes a long time to rise or makes a compressor noise has a problem.

Inspect the air springs for cracks and leaks, and check the compressor and valve block. A suspension warning light is a reason to walk away unless the seller has a detailed diagnosis. The optional rear-wheel steering is durable but should be checked for play and warning messages. The adaptive dampers can also leak or lose their damping.

The RS6 is heavy, so suspension bushes and arms wear. Listen for knocking over bumps and check the tyre wear for uneven patterns. A car with a tow bar may have been used to tow, which puts extra load on the gearbox and suspension. That is not automatically bad, but it is worth knowing.

Known weak points

The 4.0 V8 is closely related to the engine in the Porsche Panamera and the Lamborghini Urus. It is generally strong, but it has known issues. Check for coolant leaks around the heat exchanger and the water pump, oil leaks around the turbochargers and the valve covers, and a rattle from the turbo wastegates. The mild-hybrid battery and the 48-volt system can also fail, and they are not cheap to repair.

The eight-speed tiptronic is smooth and strong, but it needs its fluid changed on schedule. A car that jerks or hesitates when cold should be checked. The quattro system and the sport differential are generally reliable, but they do not like mismatched tyres. Check that all four tyres are the same brand and size.

Electrical faults are a common complaint. The infotainment, the virtual cockpit, the driver assistance systems and the parking cameras can all misbehave. Check every function, including the head-up display and the Bang & Olufsen sound system. Water ingress into the boot or the footwells can damage the electronics, so check the seals and the drains.

Buying checklist

Ask for the full service history and check that the running-in service was done. Audi RS models have specific oil and filter requirements, so look for invoices that show the correct specification. A car with a gap in its history is a risk on a complex V8.

Inspect the air suspension from cold. Start the car and watch it rise; it should be smooth and quick. Check the ride height at each corner and look for leaks. Test the rear-wheel steering and the adaptive dampers in different modes. Listen for knocking from the suspension on a rough road.

Check the tyres for matching brands and even wear. The RS6 is sensitive to alignment, and a car with worn bushes can chew through a set of tyres in 10,000 miles. Check the brake discs for cracks and measure the pads. Inspect the front bumper and the wheel arches for stone chips, and check the panoramic roof for leaks if fitted.

A pre-purchase inspection by an Audi RS specialist is essential. The air suspension and the mild-hybrid system are expensive to repair, and a diagnostic scan can reveal faults that are not obvious on a test drive. Ask for a compression test if the car has high mileage or a patchy history.

Market and depreciation

The C8 RS6 has depreciated significantly. Cars that cost £110,000 or more when new were trading at £70,000 to £85,000 for 2020 and 2021 examples at the time of writing. Later, low-mileage cars with good specification were £85,000 to £95,000. The RS6 Performance and the limited-run models sit above that.

Specification matters. The carbon exterior package, the panoramic roof, the Bang & Olufsen sound system and the 22-inch wheels are desirable. A car with air suspension problems or a patchy history can look cheap and then cost thousands. The cheapest RS6 is rarely the best value.

The RS6 is likely to depreciate further as the new model arrives, but it will not collapse. The fast estate has a loyal following, and the C8 is still a modern car with modern performance. A well-maintained car should hold its value reasonably well.

Who it suits

The RS6 Avant suits someone who wants one car for everything: family duty, long journeys, winter driving and the occasional track day. It is comfortable, fast and practical. It does not suit someone who wants a raw, lightweight sports car or a cheap commuter. It is also not a car for someone who is afraid of complex electronics.

If you do not need the space, the RS5 Sportback is smaller and cheaper, but it is not in the same league for performance. The BMW M5 Touring is sharper and more rear-driven, but it is also expensive. The Mercedes-AMG E63 Estate is more comfortable and more discreet, but it is not as fast.

Alternatives

The BMW M5 Touring is the closest rival. It has a twin-turbo V8, all-wheel drive and a more involving chassis, but it is heavier and less practical than the RS6. The Mercedes-AMG E63 Estate is softer and more luxurious, with a brilliant V8, but it is older and less high-tech. The Porsche Panamera Sport Turismo is sharper and more expensive, and it has a smaller boot.

The Audi RS4 Avant is the sensible choice if you do not need the V8. It has a 2.9-litre twin-turbo V6, 444 bhp and a more comfortable ride. It is slower, but it is cheaper to buy and run, and it is still a very fast estate. The RS6 is the flagship; the RS4 is the value pick.

How this review was compiled

This review is based on Audi's published technical and service information, owner reports from Audizine and RS6.com forums, UK specialist servicing guides and current Auto Trader listings. These figures are indicative and vary with specification and mileage.