Audi S4 Buyer's Guide

The S4 is the fast Audi that never quite got RS respect, which keeps it cheap: our two sold results are a 2003 S4 Avant at £2,500 and a 2004 S4 at £1,853. Both are B6-era cars with the 4.2-litre V8, and both prices tell you the market has already accounted for what that engine costs to keep.

Know your generations

The catalogue here centres on the B5 (1997–2002), the original S4 with the 2.7-litre twin-turbo V6, 265bhp and quattro drive: the cult favourite, endlessly tunable and increasingly collected in unmodified form. The cars our results represent are the next chapter: the B6 (2003–2005) and near-identical B7 (2005–2008) swapped turbos for a 4.2-litre V8 with 344bhp, a manual option and a soundtrack the RS4 shared. After the B7 the S4 went supercharged V6 and modern; those cars are not yet auction material.

What to pay

Two results: £1,853 and £2,500, sold in March 2026. That is running-car banger money for a V8 quattro saloon or Avant, and with a sample of two we will simply say both were mid-2000s V8 cars and neither approached four figures twice over. Qualitatively, unmodified B5s in good order trade well above this level nationally, but our data does not yet price one.

What goes wrong

The B6/B7 V8 carries its timing chains at the rear of the engine, between block and gearbox: worn chain guides and tensioners announce themselves as start-up rattle, and the repair means removing the engine, a bill that routinely exceeds what our two results say the whole car is worth. That single fact explains the prices. Beyond it, check for oil consumption, tired coil packs, and the usual quattro driveline items: propshaft centre bearings and worn rear differential mounts. The B5's twin-turbo V6 has its own list: K03 turbos of finite life, bipass valves, and control-arm kits on the front suspension that need doing roughly every other ownership. Rust is minor on all of them; galvanised shells were an Audi strength. Interiors, Recaros especially, hold up well and matter to future value.

Our view

At £1,853 to £2,500 the B6-era S4 is one of the cheapest V8 performance cars in our records, and it will stay that way: the rear-mounted chains make every high-mileage example a gamble in which the losing hand costs more than the car. Buy one only with evidence the chains and guides have been done, and then enjoy an absurd amount of engine for the money. The long-term classic in this family is the unmodified B5; the V8 cars are the bargain with a trapdoor in it.