In the late 1990s, Mercedes-Benz was one of the first automakers to recognize America's desire for a luxury-themed SUV. The original ML, while truckish in nature and plagued by early quality problems, was a solid sales success. Last year, Mercedes introduced the second-generation M-Class, and in almost all aspects it's a better vehicle. Still a midsize luxury SUV meant for five passengers, the 2007 Mercedes-Benz M-Class is now more on-road oriented thanks to a unibody structure and a revised suspension design that combine to provide improved handling and comfort. Other upgrades for the second generation include sleeker exterior styling, a higher-quality interior and new engines.

For the 2007 M-Class, Mercedes-Benz has released two new trim levels. The first, the ML320 CDI, is diesel-powered. Its 3.0-liter turbocharged engine is capable of 215 horsepower and a stout 398 pound-feet of torque and, like most diesels, provides impressive fuel mileage and range -- more than 600 miles between fill-ups is possible, says Mercedes. Buyers should be aware, however, that the ML320 CDI is not for sale in California, Maine, Massachusetts, New York or Vermont due to tighter diesel emissions standards in those states.

For maximum acceleration, there's the new ML63 AMG. A successor to the original ML55 AMG, the ML63 AMG features an all-new 507-hp V8 developed specifically by AMG's engineers. Impressively, this power comes about without the help of supercharging or turbocharging. Zero to 60 mph takes fewer than 5 seconds. This AMG model is also equipped with more powerful brakes and a sport-tuned version of the optional air suspension system. Though the point of fitting a 500-hp engine to a top-heavy SUV weighing 2.5 tons is lost on many driving enthusiasts, there's no denying that the ML63 AMG is impressive for what it is. It also happens to undercut the price of its closest competitor, the Porsche Cayenne Turbo S, by a significant margin.

When judged against other SUVs in the $50,000 price range, the Mercedes faces some very competent vehicles. The Acura MDX, Audi Q7 and BMW X5 are all-new this year, and the Cayenne, Lexus RX 350 and Volkswagen Touareg continue to be solid choices, as well. Overall, we're impressed with the 2007 Mercedes-Benz M-Class, and it should make a fine choice for shoppers valuing the ML's versatility along with the traditional Mercedes traits of quality, prestige and safety. Downsides? The lack of a third-row seat is an obvious omission, but Mercedes dealers will no doubt point you to the R-Class or new GL-Class if you truly need six- or seven-passenger capacity. The only other issue that will likely give you pause is price; equipped with a fair number of options, the M can often end up being one of the more expensive vehicles in this segment.

The 2007 Mercedes-Benz M-Class is a midsize luxury SUV that seats five. There are four trim levels available: ML350, ML320 CDI, ML500 and ML63 AMG. The ML350 and 320 CDI are equipped similarly and come standard with 17-inch wheels, heated exterior mirrors, Tele Aid, dual-zone automatic climate control, power front seats, maple wood interior trim, the COMAND interface and a CD player with an auxiliary input jack. The ML500 has this equipment plus 18-inch wheels and heated front seats. The ML63 AMG features special interior and exterior styling details, as well as a sport-tuned air suspension, 20-inch wheels, stronger brakes and sport seats.

For the regular MLs, a large collection of options -- most of which are bundled in packages -- are available for further customization. Highlights (depending on the trim level) include an AMG sport appearance package with 19-inch wheels, an adjustable air suspension, park assist, adaptive cruise control, adaptive xenon HID headlights, a sunroof and a power liftgate. For the interior, MB offers tri-zone climate control, deluxe multicontour front seats with heaters, leather upholstery, a premium Harman Kardon surround-sound audio system, satellite radio, a navigation system and a rear-seat entertainment system.

Each trim level has a distinct engine. The ML350 has Mercedes' corporate 3.5-liter V6; it develops 268 hp and 258 lb-ft of torque. A 3.0-liter turbodiesel V6 is found in the ML320 CDI. It provides 215 hp and 398 lb-ft of torque and has EPA fuel economy estimates of 21 mpg city/27 mpg highway. The 5.0-liter V8 in the ML500 is capable of 302 hp and 339 lb-ft of torque. For the ML63 AMG, Mercedes installs a 6.3-liter V8 that makes 503 hp and 465 lb-ft of torque. All models are fitted with a seven-speed automatic transmission and all-wheel drive. Maximum tow capacity is 5,000 pounds.

Standard safety features on the 2007 Mercedes-Benz M-Class include traction and stability control, antilock disc brakes with brake assist, front side-impact bags and full-length head-protecting side-curtain airbags. Hill descent control and hill assist features are also included. The ML's performance in NHTSA crash testing was impressive, as the Benz posted perfect (five star) scores in both frontal- and side-impact testing. The IIHS gives the SUV a top score of "Good" for its protection of occupants in frontal-offset crashes.

Steering is precise, but doesn't offer much feedback and feels a little dead in the center. The brakes, however, supply a sure-footed pedal and stop this SUV quickly. Despite some body roll, the 4,788-pound, all-wheel-drive ML is a predictable and stable handler. In terms of acceleration, the ML350 possesses plenty of passing power, but feels a bit shy on torque from a stop. The new ML 320 CDI, being diesel-powered, is almost the opposite. If you want more punch off the line, spring for the V8-powered ML500 or ML63 AMG. The latter is capable of hitting 60 mph from a standstill in fewer than 5 seconds.

Large helpings of bird's eye maple wood and brushed aluminum trim help define the handsome instrument panel. Storage space is adequate, and the front console features very large cupholders. In the back, passengers have more than 39 inches of legroom to stretch out in, which is nearly 6 inches more than the RX 350 offers. Folding down the rear seat provides a maximum 72 cubic feet of cargo room.