The MERCEDES-BENZ S CLASS (2017-20) S400L 4DR SALOON LWB 2.9D DPFR SS 340 EU6 AMG LINE EXECUTIVE 9G-T+ AUTO is a long-wheelbase luxury saloon, sitting at the top end of the UK executive-car market. Its stretched cabin prioritises rear-seat space and comfort, while AMG Line styling gives this chauffeur-friendly flagship a sportier appearance. It is a large, premium alternative to conventional family cars, rather than a practical city runabout. mycarcheck.com has recorded 32 look-ups, but they cover just two distinct VINs, so treat these figures as a small snapshot rather than a broad reliability verdict. Across those checks, average private-sale valuation was £35,100, average recorded mileage 65,000 miles and annual mileage 7,000. The cars averaged half a previous keeper, suggesting little ownership turnover in this limited sample. Suited to executives and families seeking comfort, it combines a strong diesel engine with a smooth automatic. Rivals include BMW 7 Series and Audi A8, but the S-Class is famed for calm ride, refinement and prestige; running costs may be high.