Unfortunately, history has shown that neither diesels nor the Mercedes-Benz R-Class are popular in North America. So why, then, would Mercedes drop its brand-new BlueTec diesel engine into the 2009 Mercedes-Benz R320 Bluetec and sell it here?
The answer may be surprisingly simple: it may well be the best version of the R-class presently available to Americans. Though the $1500 cheaper R350, with its gasoline-powered V-6, may appeal to those on a budget, the power, refinement, and efficiency of the R320 make it the more compelling option for most customers.
What is it?
This may well be the most frequently asked question surrounding the R-class since its debut in 2002. Sharing its underpinnings with the M-class SUV, riding on a wheelbase longer than an S550, yet devoid of the European V-class minivan's sliding side doors, the R-class seems to defy most vehicle categories. Mercedes' official classification of a "sports tourer" does little to clarify the situation.
Despite the conventional rear doors, the R320's three rows of seating, tall ceiling, and acres of cargo room (provided at least one row of seats is folded) certainly give it the functionality of a minivan.
Some, however, may see it as an alternative to an E-class wagon. And while the sedan version of the E-class gets the Bluetec diesel for 2009, the wagon does not. Likewise, you'd be hard pressed to seat more than five in any E350 wagon, unless your third-row passengers are under five feet tall and enjoy facing backwards.
We'd have to agree with Mercedes-Benz that the R-class doesn't look like a minivan - but it's not drop-dead gorgeous, either. Though everything aft of the A-pillars resembles a lower-slung GL-class SUV, the front fascia is an odd mixture of the headlamps from the E-class and the hood form from an SLK roadster. The large, ovoid lights seem particularly out of place - a situation we hear will be rectified with the next-generation R-class.
Apart from the unique looks, the R320's sheer length helped us pick it apart from a sea of crossovers in most parking lots. Measuring 203 inches from bow to stern, the R320 is approximately three inches longer than a GL320 SUV. Adult passengers in both the second and third rows will appreciate the large dimensions, but parents may not - the rear doors are quite long, making loading small children and safety seats in parking lots a bit of a hassle.
It's what's inside that counts
Once inside, however, most passengers are unlikely to complain about their surroundings. We're hard pressed to recall a minivan so luxuriously appointed - a situation for which we can thank the optional Premium Package 2.
The $8000 package includes such gizmos as parking sensors, a rear-view camera, a Harmon-Kardon surround-sound system, and three-zone automatic climate control. Our R320 was also fitted with Tele Aid ($650), keyless entry and ignition ($1130), and a rear-seat entertainment package ($1000). The latter, which adds a pair of eight-inch LCD screens to the front seatbacks, lets second-row passengers watch DVDs or play video games. Third-seat passengers can enjoy the panoramic sunroof ($1050), which lets them enjoy their surroundings to the fullest.
Even without these luxuries, the R320's interior is still well built, using materials that are nicely grained and relatively soft to the touch.
Still, those aspects of the R320 have not significantly changed over the past six years - it's what's under the hood that has. Though much of the 3.0-liter turbo-diesel V-6 is carried over from the outgoing R320 CDI, the 2009 model is the first application of Mercedes' latest Bluetec emissions system. In the R320, ML320, and GL320 Bluetec SUVs that means using an active approach at controlling nitrous oxide exhaust emissions.
After passing exhaust gasses through two catalytic converters and a particulate filter, a liquid urea solution (which Mercedes calls AdBlue) is injected into the exhaust. As a result of the urea's ammonia, nitrous oxide molecules are then converted to water and nitrogen. According to Mercedes, the process is capable of converting up to 88 percent of all nitrous oxide emissions.
Owners shouldn't worry too much about the process. Contrary to the images its name may imply, the urea within AdBlue carries no scent, and owners won't have to fuss with it, anyways - dealers will top-off the tank during scheduled maintenance sessions.
The Diesel Drive
The BlueTec system may be a new addition to the 3.0-liter V-6, but its torque and economy are more notable. Although the V-6's power drops to 210 hp for 2009, it still produces a whopping 389 lb-ft of torque at 1650 rpm.
That's a considerable amount of pulling power, and it does well moving the 4940-lb R320. It's also able to deliver some impressive fuel economy: The EPA rates the R320 at 18/24 mpg city/highway, but we averaged between 22 and 24 mpg in our daily commutes around town.
What the engine doesn't deliver, however, is the 'sport' implied by 'sports tourer.' Mercedes claims the R320's 0-60 mph time is a mere 8.6 seconds, but the crossover doesn't feel fast, even in 'sport' mode. Perhaps that's just as well - we most enjoyed our time in the R-class when both the seven-speed automatic transmission and the Airmatic suspension were set in 'comfort' modes
Will It Succeed?
That depends on your definition of success. Though the Bluetec diesel offers a mix of power, economy, and refinement few other engines can deliver, it'll take some convincing for North American consumers to buy in. Some may have bad memories of slow and smoky diesels of yore. Another stumbling block is that diesel fuel has been running nearly a dollar per gallon more than regular gasoline.
Those who do decide on a diesel may look elsewhere in the Mercedes-Benz portfolio. Posh and practical the R320 may be, the slow sales of the R-class in general suggest it may be the answer a question no one really asked. Though the diesel engine addresses the issue of fuel economy, we think most Americans looking at a Bluetec Mercedes will opt instead for the more conventional ML320 and GL320 SUVs instead.