The AUDI A4 (2005-08) RS4 4DR SALOON 4.2 QUATTRO 420 is a high-performance, four-door saloon: a practical family-car shape with the character of a sports car. Its powerful 4.2-litre petrol engine and four-wheel drive make it a distinctive, premium choice in the UK used-car market, rather than an everyday budget A4. mycarcheck.com has recorded 3,068 look-ups across 802 different VINs, giving a substantial snapshot of interest. Checks show an average private-sale valuation of £10,900 and average recorded mileage of 97,000 miles; average annual mileage is 3,000. The average keeper count is about six, so check service records, condition and ownership history carefully. The RS4 suits enthusiasts wanting four seats, a boot and year-round grip, with an engaging drive; it is less suited to budget commuters because fuel and running costs can be high. Against BMW M3 rivals, it stands out for all-weather traction, understated looks and its blend of pace and practicality.