The redesigned 2012 Mercedes-Benz M-Class is a perfect example of subtle evolution. When you've got something good going, why make radical changes? As such, the newest Mercedes M-Class, despite having all-new sheet metal, is instantly recognizable as the brand's popular midsize SUV. Styling is cleaned up a bit, as the grille returns to a more classic Mercedes look while the profile keeps the M's familiar greenhouse. A few newer styling cues are seen in the sculpted hindquarters and wide taillights, both inspired by the E-Class.

Inside the 2012 M-Class, there is a greater sense of luxury, with plenty of handsomely stitched leather, more rounded design cues than the rest of the Mercedes line and up-to-date switchgear quality and functionality. This year, there are also a few different interior styling options to choose from, such as quilted leather upholstery and matte-finish wood accents. Although the second-row seat can accommodate three passengers, it is sculpted to provide greater comfort for two. No third-row seat will be offered at first, but one will become available a few years down the road to appease that vocal minority who've asked for one.

Under the new skin, key improvements have been made in both performance and fuel efficiency. The volume-selling ML350 V6 has more power and delivers better fuel economy than before, as does the ML350 Bluetec turbodiesel. Then there are the V8-powered models, the ML550 and ML63 AMG, for those who want their SUV to accelerate like a sports car (and don't mind the commensurate appetite for fuel). This year there is no hybrid M-Class. Our pick of the litter is the Bluetec, which offers the stout power down low that makes a near-5,000-pound SUV feel light on its feet, while also returning respectable fuel efficiency.

More powerful, more capable and with a nicer cabin than ever before, the 2012 Mercedes-Benz M-Class nonetheless has some tough competition. Its chief rival is once again the BMW X5, but there are also the less expensive Acura MDX and Lexus RX as worthy choices. As for similarly priced and sized rivals, the aforementioned X5 and the Porsche Cayenne both offer more driving involvement and response, especially from their steering. As any of these will provide more than enough luxury and performance for most folks, we'd encourage you to conduct back-to-back test-drives of any that strike your fancy.

The 2012 Mercedes-Benz M-Class is a five-passenger midsize luxury SUV available in ML350, ML350 Bluetec, ML550 and ML63 AMG trim levels.

The ML350 and ML350 Bluetec are equipped similarly with standard 19-inch wheels, a sunroof, a power liftgate, foglamps, dual-zone automatic climate control, a tilt-and-telescoping steering wheel, eight-way power/heated front seats, reclining rear seats, MB-Tex premium vinyl upholstery, the COMAND electronics interface, Bluetooth, the TeleAid emergency telematics service and an eight-speaker sound system with HD radio, a CD player and USB/auxiliary jacks.

The ML550 adds 19-inch AMG wheels, running boards, a trailer hitch and rear seat side airbags. Other than the wheels, all of these items are available on the 350 trims.

Options include the Premium 1 package, which includes a rearview camera, power-folding mirrors, auto-dimming rearview/sideview mirrors, a power tilt-and-telescoping steering wheel, driver memory functions, a navigation system, voice controls, satellite radio, an iPod interface and 10GB of digital music storage. The Premium 2 package includes all Premium 1 equipment plus keyless ignition/entry, heated/cooled cupholders, a Harman Kardon surround-sound audio system and ambient cabin lighting.

There are other packages as well. The Dynamic Handling package includes 20-inch alloy wheels and an air suspension with adaptive dampers and stabilizer bars. The Lighting package includes adaptive bi-xenon headlights (with washers) as well as corner-illuminating lights. The Lane Tracking package includes blind-spot warning and lane departure warning. The Driver Assistance package adds active cruise control (with active PreSafe braking) to the contents of the Lane Tracking package. An off-road package with selectable terrain modes will debut a bit later in the model year.

Individual option highlights include a panoramic sunroof, active park assist, a night vision camera, triple-zone climate control, full leather seating, ventilated front seats, heated rear seats, a rear seat entertainment system, two-tone leather upholstery and different cabin accents (metallic and wood).

The ML63 AMG gets a twin-turbo V8, active roll stabilization, stronger brakes, AMG-tuned suspension and steering, 20-inch wheels, special leather upholstery, sport seats and unique styling elements inside and out. The Premium 2, Lighting and Lane Tracking packages are standard as well. The AMG Performance package raises engine output and adds a higher top speed. Also optional are 21-inch AMG wheels along with most of the other trims' extra equipment.

The ML350 comes with a 3.5-liter V6 that produces 302 horsepower and 273 pound-feet of torque. A seven-speed automatic transmission and all-wheel drive are standard for the ML350 as well as all other M-Class models. In Edmunds performance testing, an ML350 went from zero to 60 mph in 6.8 seconds, which is average for its class. EPA-estimated fuel economy is 17 mpg city/22 mpg highway and 19 mpg combined.

The ML350 Bluetec has a 3.0-liter turbodiesel V6 that utilizes 50-state-legal clean-diesel technology. It produces 240 hp and a prodigious 455 lb-ft of torque. Mercedes estimates that it will go from zero to 60 in the same time as the gas ML350, but fuel economy improves to 20/27/22.

The ML550 gets a 4.7-liter twin-turbo V8 that produces 402 hp and 443 lb-ft of torque. Mercedes says it'll hit 60 mph in 5.3 seconds. EPA-estimated fuel economy is 15/20/17.

The ML63 AMG gets a 5.5-liter twin-turbo V8 that produces 518 hp and 516 lb-ft of torque. The AMG Performance package bumps this engine up to 550 hp and 560 lb-ft. Mercedes says the ML63 will hit 60 mph in 4.7 seconds in its standard form, while the Performance package knocks a tenth of a second off that. Fuel economy stands at 14/18/15.

Standard safety equipment includes antilock brakes, traction and stability control, hill-start assist and hill-descent control, active front head restraints, the mbrace emergency communications system, PreSafe (it anticipates an imminent crash and automatically takes measures to better secure occupants), front and rear side airbags, side curtain airbags and a driver knee airbag. The optional Lane Tracking package includes blind spot warning and lane departure warning.

In Edmunds brake testing, an ML350 came to a stop from 60 mph in 114 feet, which is outstanding for such a heavy vehicle with all-season tires.

Though the acceleration numbers of the gas and diesel V6s are similar, there are two distinct personalities here. As expected, the turbodiesel V6 provides strong low-end grunt, which tapers off as the revs climb. The gas V6 takes the opposite tack, feeling a bit soft off the mark but giving a more potent higher-rpm rush. If you want more power or just the status of the numerically higher badge, the turbocharged ML550 and ML63 AMG will happily oblige. Both models are exceptionally quick. No matter which ML you choose, braking performance is strong and reassuring.

On a winding road, the 2012 Mercedes-Benz ML350 tends to roll a bit when pressed, but the ride is compliant without being floaty. Those who want more of a sport sedan flavor in their SUV can opt for that Dynamic Handling package that does an impressive job of quelling body motions. The new, all-electric steering system is a bit of a disappointment, however, as it's overly light and doesn't provide the sort of subtle feedback we've come to expect from Mercedes-Benz. The ML63 is better in this regard, as you would hope from such a high-performance machine.

The 2012 Mercedes-Benz M-Class features an upscale cabin and seating for five. This year brings more personalization options as well, with two-tone upholstery and various wood and metallic accents to choose from. The more rounded dash design reminds us more of the distantly related Jeep Grand Cherokee in its appearance than its squared-off Mercedes siblings, but that's more of an aesthetic critique. The COMAND interface works well and allows the driver to easily select the car's more complicated infotainment options without making simpler commands too difficult.

Passenger room is impressive, as the M-Class offers more rear legroom than most of its competitors. There's no third row offered, though. With the rear seats in place, there is a total of 36 cubic feet of luggage space. When the seats are folded flat, this expands to 71 cubes -- an average figure for this class of vehicle.