Which used Audi A6 saloon should I buy?
The diesels are best: they are far more common than the petrols, and hold their value better. The entry-level 138bhp 2.0-litre TDI performs well in such a large car. If you want more performance, then the smooth 178bhp 2.7-litre V6 is the next best option, with the 233bhp 3.0-litre V6 diesel the quickest, but also the rarest.
Consider a petrol model, though, if the price is right. The turbocharged 2.0-litre has 165bhp, then there are three V6s and two V8s with between 177 and 345bhp. The 2.0 and smallest V6 are the best options.
Quattro four-wheel drive is an option with the mid-sized engines and standard on the largest. While it does improve handling and traction, it doesn't make an already accomplished car an awful lot better. The automatic gearboxes are smooth and feel well matched to the engines.
Opt for SE trim and you'll get a good kit list, including climate control, CD player, four electric windows and cruise control. The S line adds stiffer suspension and racier cabin detailing. Metallic paint is essential for good resale value - as is sat-nav and leather seats on anything larger than a 2.0-litre model.