Besides the navigation system and Sirius radio, the wide variety of factory and dealer-installed options available for--but not fitted to our example of--the R350 includes Parktronic; a power tailgate; rear side air bags; a rear-seat entertainment system with LCDs integrated into the back of the front headrests; bixenon headlights with curve and corner illumination; and an iPod docking system that includes steering-wheel-mounted controls and a visual display.
With a 4,841-pound curb weight, true sport driving is not in the 2006 Mercedes-Benz R350's repertoire. Although the 3.5-liter V-6 is helped by the seven gear ratios of the 7G-Tronic automatic transmission, as well as the optional Airmatic air suspension with adaptive damping, two and a half tons does not make for sports-car-quick reflexes.
Still, the R350 works well for its true intended purpose: touring at a quick pace. Here, both its drivetrain and suspension perform favorably, with nice acceleration, a comfortable ride, and very decent handling for a vehicle of its size.
Power comes from Mercedes-Benz's newest 3.5-liter V-6, which has four valves per cylinder, as well as dual overhead camshaft heads instead of the previous three-valve, single overhead cam heads. The twin-cam design allows the phasing of each camshaft to be individually controlled for improved efficiency and power, along with lower emissions and fuel consumption. Electropneumatically driven, electronically controlled tumble flaps in each intake duct improve airflow and also help decrease fuel consumption and emissions. A balance shaft ensures the smooth operation expected from a luxury-vehicle engine.
The engine's maximum 268 horsepower (at 6,000rpm) and 258 pound-feet of torque (between 2,400rpm and 5,000rpm) are enhanced by the seven-speed automatic. The 2006 Mercedes-Benz R350 did well on both, with quick full-throttle acceleration (according to the manufacturer, a 0-to-60mph time of 8.1 seconds) and an observed fuel economy of just less than 20mpg in mostly highway and high-speed secondary road driving. EPA-mileage figures are 16mpg in the city and 21mpg on the highway.
Like the ML-Class SUV, all R-Class models have the 7G-Tronic automatic transmission with the Direct Select column-mounted shifter for basic forward/reverse/park control, as well as rocker switches on the back of the steering-wheel spokes for manual shifting. This design frees up the console for extralarge cup holders--this is a vehicle made in the Alabama plant, mostly for the American market--and shifting gears with the rocker switches becomes second nature to operate after a little familiarization.
Nevertheless, due to the wide torque band and the transmission-control computer's ability to adapt shifting style to the driver's needs, shifting manually isn't vital. And the R350's character doesn't demand rough manual treatment, as it's more about relaxed cruising in comfort rather than frenetic speed.
The 2006 Mercedes-Benz R350's suspension design is conventional and all independent, with double wishbones in front and a four-link system in the rear. The optional Airmatic suspension replaces the front coil springs and the rear air springs with pneumatic spring struts and active-shock damping from the active damping system (ADS). There are two driver-selectable ranges, Comfort and Sport, the latter of which interestingly is the default mode.
We initially found that the R350 felt like a large, softly sprung luxury car. That was fine on the freeway and around town, but we were not looking forward to the back-road portion of the test. The Airmatic/ADS-equipped R-Class did better than anticipated. The harder it was pushed, the firmer the suspension became, although never at the expense of comfort.
Another feature of the Airmatic system is adjustable ride height. This feature automatically lowers the R350 at speeds of more than 70mph to decrease wind resistance and improve stability, and the car can be raised about an inch at low speeds for better clearance. The R350's aerodynamic design results in low levels of wind noise at all speeds.
Full-time all-wheel drive, with a 50/50 static front/rear torque split, is standard, and the latest version of the Mercedes-Benz 4ETS traction-control system further improves traction by activating the brake on any wheel or when wheels lose traction, as determined by the ABS wheel sensors. In keeping with the R-Class's luxury-transportation mission, traction control is all-weather rather than performance based, and we noticed no lack of traction on wet roads.
If it's a safety item or technology in a modern car, odds are it was invented by--or for--Mercedes-Benz. The R350 has the full complement of Mercedes active and passive safety features.
The R350's unibody structure was designed and built to protect all occupants in the event of a crash. Repair costs for minor front or rear collisions can be reduced because of use of crash boxes, which are bolted rather than welded in place. Further protection comes from front and rear crumple zones and a strong safety cage around the passenger cabin. All seating positions have three-point safety belts, and dual-stage front, front side, and full-length window air bags are standard.
The 2006 Mercedes-Benz R350's brakes are four-wheel antilock discs, with electronic brake-force distribution and brake assist. An ESP electronic-stability system, which helps control excessive oversteer or understeer, is standard.
Two optional systems not on our test car are noteworthy. Neck-Pro front head restraints can protect the driver and the front passenger in a rear-end collision by automatically moving the headrests forward and upward to better support the head and reduce the chance of whiplash. The Pre-Safe system links sensors from the ESP and brake-assist systems to detect a possible impending accident, then tightens the driver- and front-passenger seat belts in preparation. If the front-passenger seat has memory, the seat will be moved to a safer position and automatically returned if the crash doesn't occur. If the car is fitted with a sunroof, the roof will be closed if there is the chance of a rollover.
The Mercedes new-vehicle warranty for materials and workmanship lasts 48 months/50,000 miles and can be extended at extra cost. The extended warranty is transferable to the next owner if the car is sold before the end of the warranty period. The first scheduled maintenance is free of charge.
As of this writing, the Mercedes-Benz R-Class has not been rated for crash safety by the federal government.