Top 10 Most Extreme Luxury Sedans

Because the conventional E-Class sedan is about 175 pounds lighter than its CLS twin, supplying both cars with the same AMG 507-hp V8 should give the E63 slightly better acceleration, though Mercedes claims identical zero-to-60-mph times of 4.3 seconds. Choosing the arguably less stylish E63 saves $7,600, however, and provides the most conservative-looking luxury performance sedan on the market. ***

BMW claims that the M5's 5.0-liter, 500-hp V10 uses Formula One technology, and certainly among our 10 extreme sedans, the M5 is the most race-worthy: It's more about high-speed performance and dynamics than sheer torque in a straight line; lap times rather than zero-to-60-mph times. The M5 can be ordered with a sequential-manual transmission or a conventional manual, both six speeds; the latter is far smoother. ***

At $182,275, it's easily the most expensive car on our list, and for that you get a twin-turbo V12 producing 603 hp and a stunning 738 pound-feet of torque, a tsunami of force equaled only by the far more expensive ***

Mercedes calls this car a "four-door coupe," but we call it a sedan, albeit with less rear-seat space and headroom than the E-Class, whose platform it borrows. Its hand-built engine is a 6.2-liter, 507-hp V8 with superb torque characteristics ***

A true enthusiast's Caddy, the CTS-V has a 400-hp Corvette V8 with a six-speed 'Vette manual transmission ***

A base Audi A4 has a 2.0-liter, 197-hp four-cylinder; the RS 4 more than doubles all those numbers with a 4.2-liter, 414-hp V8. It's one of the most extreme sedans on the list. Extensive use of aluminum components and body panels help to balance out weight distribution and give the all-wheel-drive RS 4 superb handling, also thanks to a substantially wider track front and rear that is reflected in its strongly bulged fenders. ***

With a supercharged, 469-hp version of Cadillac's dual-overhead-cam Northstar V8, this is the most powerful production Cadillac ever. But it costs nearly twice as much as the excellent 320-hp STS V8 and doesn't bring any significant benefits beyond the extra power. Performance is impressive, but it can't compete with the Brits and Germans in interior amenities. An STS with a supercharger doesn't merit a $77,485 price tag. ***

For just above $40,000, this is by far the best bargain among super sedans. It is less luxurious and has a rougher ride than the competition, but the comparative harshness adds to its sporty character. At 425 hp and 420 pound-feet of torque its 6.1-liter V8 is the biggest and strongest Hemi engine Chrysler offers. It's mated to a sophisticated, Mercedes-developed five-speed automatic transmission. ***

Jaguar's big sedans have distinctive and delightful ride and handling qualities but more snug interiors than some of the competition. The "R" version of the XJ line continues with last year's 400-hp supercharged V8 and six-speed automatic, but we're eager for Jaguar to fit the new 420-hp version and sequential-shift transmission from the all-new XKR sports car. ***

A superb balance of luxury, comfort and high performance, this joins the BMW M5 as one of two 10-cylinder cars on our list. It doesn't feel as extreme as some of the sedans and rewards delicate steering, throttle and braking input with precise handling and performance. Its 450-hp engine is based on the Lamborghini Gallardo's V10 block but is thoroughly reworked. Audi's Multi-Media Interface is more effective than competing menu-screen controllers. ***