Think of diesel and there it is, swerving and coughing down Stereotype Road: a stinking, clattering smogmobile, reminding everyone why we will never ever buy into that whole diesel thing again – no matter what your buddy says about longevity, efficiency and performance. And if you’re too young to think of ol’ clack and clatter, right about now you’re probably picturing a hairy, lanky hippy with fast food oil in her bathtub.
Hey Marge – you ready to mix up another batch of homemade?
Mercedes-Benz wishes you’d stop. It would humbly like you to think about diesel in a more positive way, say, as a serious solution to our fuel and environmental woes. To that end, the automaker hopes more than a few people lift up their hands to the idea of diesel, and are convinced that thousands will – once they experience their newest entrant into a long and illustrious history of diesel powertrain development: Bluetec.
Indeed, Rudolph Diesel – that crazy-smart German who came up with the diesel idea in 1892 – would be proud. Mercedes-Benz has managed to develop a V-6 diesel engine that consistently beats all competitive gasoline comers in terms of emissions and fuel economy. It actually meets clean-air certification in all fifty states. That’s no easy feat, thanks to California’s strict emissions regulation7s, and one that Mercedes has only been able to accomplish with this version of Bluetec. Last year’s exquisite E 320 was approved for 45 states. What’s more, they did it with little sacrifice to the experience of piloting a ‘Benz down the road.
After two days spent driving 2009 model R 320, ML 320 and GL 320 Bluetec diesels, there are but a few differences between Bluetec and its gasoline equivalents, at least from the perspective of the steering wheel. The engine is exceedingly quiet, save for slight diesel chatter at low revs under acceleration; it applies energy smoothly through the seven-speed transmission during typical driving circumstances such as stop/start and cruising. Best of all, it offers none of the smoke and noise that turned off generations of commuters to the idea of diesel. Unfortunately, there’s a lack of passing power, given the weight of the SUVs and the engine’s power rating of 210 hp. Most of the torque (about 400 lb.-ft.) seems to be had at lower ranges, with less push available at higher speeds.
In exchange for these minor performance issues, the Bluetec system will likely deliver surprisingly low emissions (Bin 5), typical diesel dependability (will run forever) and get great fuel mileage (we averaged around 24 mpg) – not to mention a nice, long fuel range: Mercedes-Benz officials say that a typical Bluetec SUV will go 600 miles on one tank of fuel, a nice benefit for commuters who’d rather stop at Starbucks than Chevron.
Ah – but about filling the tank.
Up to now we’ve ignored the real issue here: diesel costs around $5.00 per gallon, isn’t available in enough suburban outlets, and, well, is going for $5.00 a gallon – did we mention that? There’s no easy way around this one for Mercedes-Benz. Only if diesel prices go down will Bluetec appeal go up for car buyers who react more to the pain at the pump than logic and common sense. Another possible complication is the urea issue: In order to get that coveted all-state certification and make their Bluetec clean, Mercedes-Benz added a urea tank component to their system. In brief, the process mists urea – called AdBlue by Mercedes – from an onboard tank into hot exhaust gases. When that happens, the urea turns to ammonia, which then converts the harmful NOx exhaust into nitrogen. Compared to the E 320, the urea is an added step in the process. The potential problem is if/when the system breaks, or needs to be filled. If you run out of urea and are unable to find a place to refill it, you get 20 ignition starts before the vehicle’s electronic Arnold locks you out and you have to call up a flatbed with directions to the local Mercedes-Benz dealer. Mercedes-Benz officials counter that replenishing urea is easily handled during normally scheduled service visits, though the rate of usage does go up under load, so people who tow or drive often or under weight may need to have the tank filled slightly more frequently than standard service would require. For buyers with trailers or folks who plan on keeping their Mercedes diesel for a long time and don’t wish to use dealer service, the addition of urea to the mix does create some minor complications.
Those types of potential complications are a small price to pay for the benefit of Bluetec, however, especially for those luxury buyers who are loathe to give up their SUVs. An excellent system that gives efficiency and environmentally-minded buyers a solid choice, its slight flaws should not deter someone from taking a long hard look at diesel as a viable replacement. Given that nowadays we should all be efficiency-and environmentally-minded, one hopes that the price of diesel comes down enough so that car buyers will forget about Stereotype Road and consider giving diesel a fair shot at winning its place in America.