***Deal pending****, , The M-Class, which debuted as a 1998 model, is built at Mercedes-Benz's plant near Tuscaloosa, Ala. Buy any Mercedes-Benz this year and scheduled maintenance is free for four years or 50,000 miles, which matches the duration of the warranty., , Along with Volvo, Mercedes-Benz has always been a leader in safety and innovation. All M-Class models now come with side-impact airbags for the rear seats as well as the front seats. A new five-inch LCD display with touch controls in the center console operates climate, audio and telephone functions, and on the ML430 and ML55 it also operates the standard GPS-based navigation system. , , Interior, All versions seat five, and the split rear seat folds for additional cargo space. Leather is standard on the ML430 and ML55, optional on the base ML320., , Exterior, Wider fender flares, rocker panel extensions, chrome grille accents and fog lights integrated into the front bumper give the ML55 a unique appearance. The ML55 rides on 18-inch tires, the others on 16- or 17-inch tires. All models have four side doors and a one-piece liftgate., , Under the Hood, The model designations denote engine size. The ML320 uses a 3.2-liter, six-cylinder with 215 horsepower; the ML430 a 4.3-liter V-8 with 268 horsepower; and the ML55 a 5.5-liter, V-8 with 342 horsepower, which is three less than the Chevrolet Corvette. , , All come with a permanent 4WD system that automatically distributes power among the four wheels as needed. Unlike rivals such as the Lexus RX300 and new BMW X5, Mercedes says the M-Class is a true off-road vehicle.