First unveiled in mid-2005, the W221 S-Class offered better performance than the W220 and greater cabin space, at the cost of a slight increase in size. Mercedes also upped the ante in terms of the interior spec, with finer leather, more expensive wood and improved metal finishes, plus the latest in safety technology - including Pre-Safe and Brake Assist.
Imperious ride quality was assured with Airmatic air suspension and Active Body Control, while other goodies included Speedtronic radar-controlled cruise control, headlights which swivelled around corners and Night View Assist. The striking 2006 S63 AMG version came with a load of extra AMG kit on top and, most importantly of all, a hand-assembled high-revving V8 pumping out 525hp and 465lb ft of torque.
Now with a seven-speed AMG automatic transmission, performance remained ample despite the hefty 2,070kg kerb weight. Limited to 155mph, the official 0-62mph time was 4.6 seconds, and as expected the S63 felt commanding cruising at any speed. What was more of a surprise was just how well it dealt with corners - the latest iteration of Active Body Control eradicating most of the anticipated dive and pitch, and allowing the bulky S63 to behave more athletically in most situations.
The even mightier S65 AMG took things to yet another level between 2006 and 2013. With its biturbo V12 delivering a whopping 612hp and an incredible 737lb ft of torque. Enough to launch the two-tonne rear-wheel drive limo to 62mph in just 4.4 seconds, it also meant Mercedes had to stick with the stronger five-speed auto transmission. An extreme machine in every way then, with a list price starting at £145,365 and many owners adding more optional extras.
A facelift arrived in 2009 with largely cosmetic changes, the Active Body Control now provided enhanced crosswind stabilization though and Torque Vectoring Braking was also added. By the time W221 production ended in 2013, UK buyers had snapped up 224 S63 AMG Saloons and 71 S65 AMGs - nearly all of which are still around today.
That strong supply means prices are lower than you might expect. Good examples fall into the £16,000 to £30,000 price range - to put that into context, the list price for a new entry-level C200 SE C-Class Saloon is £29,035. Reliability is way better than the W220's and the AMG versions seem to suffer even fewer problems than the less potent models. "Just watch out for audio tuners which can fail," Steve Dickens points out. "And bear in mind that there's no spare wheel - and the gearbox (which is strong) can suffer with internal control unit problems."
Interestingly, tuning proved pretty popular even with new S63 AMG buyers: "The W221 is probably the better choice for modification, especially if there is a cost limitation, as it has a more modern chassis than the W220 but is relatively easier to tune than the W222," Robert Redman points out. Some owners have removed the exhaust catalysts as part of their performance tuning, but remember your car will need at the very least sports cats to pass the annual MoT emissions test.
CKS's Chet Sharma prefers the S65 though: "I would personally opt for the S65, it effortlessly combines everyday driving with the knowledge it can overtake any vehicle with ease. Wafting miles away in absolute luxury." And Olly Stoner agrees: "The S65 AMG is a brutal car with epic performance. The ultimate luxo barge. Pretty well screwed together too, but new brakes are colossal money."
Buy if: you fancy the best value AMG Mercedes saloon on the market
Don't buy if: you're expecting to get your money back any time soon
We found: 2008 S63 AMG Saloon, Black, full main dealer service history, 74k miles, £22,950
Price Guide
Poor: Under £16,000
Good: £16,000 to £30,000
A1: £30,000+
Special Editions: Low-mileage W221 S65 AMGs can sell for as much as £45,000