After two concept previews, Mercedes-Benz at last rolled out the production version of its R-class SUV/wagon/crossover whatever, which goes on sale late this year. This is a big boy, stretching 203 inches, riding a 126-inch wheelbase, and tipping the scales at some 4800 lbs. The R-class ferries a half-dozen passengers in six individual chairs. With the four rear seats folded, it carries 72 cubic feet of cargo. Mercedes' newest entry will be sold here in two versions, the six-cylinder R350 and the V-8 R500; both have standard 4Matic four-wheel drive with a standard torque split of 50/50. The R350 uses Mercedes' new 3.5-liter V-6, with dual overhead camshafts and four valves per cylinder. It makes 268 hp and 258 lb-ft of torque. The R500's 5.0-liter V-8 is from the older, SOHC, 3-valves-per-cylinder engine family. Its output is 302 hp and 339 lb-ft of torque. Both engines use the same 7-speed automatic transmission, which is controlled by a small, BMW 7-series-style column shifter (to select P, R, and D) along with up- and downshift buttons on the back of the steering wheel spokes. The standard air suspension lowers ride height by one-half inch at speeds above 77 mph, or, at low speeds, can raise the ride height by three inches for additional ground clearance. Among the sticker-fattening options are an extra-large "panorama" sunroof, an entertainment system with dual screens in the back of the front headrests, swiveling bi-xenon headlights, a power liftgate, keyless ignition, and nineteen- or twenty-inch wheels, the latter part of an AMG appearance package. No full-on, supercharged, 500-plus-hp, AMG version has been announced yet, but with the once-exclusive AMG models proliferating throughout the Benz lineup, it can't be far behind. Base R-class models will begin around $50,000 and will be built alongside the new ML in Merc's Alabama plant.