Several European automakers – including Mercedes-Benz — are banking that U.S. consumers can see past the 1970s stereotypes of diesel engines and see them for the clean, reliable and fuel-efficient powerplants that they are. But while diesel engines do present several advantages over their gasoline counterparts, consumers still have plenty to be wary about.
While some U.S. clean diesels – such as Volkswagen ’s Jetta TDI – rely on a downstream NOx trap to earn their 50-state legal certification, most will use urea injection to pass stringent U.S. diesel requirements. Mercedes-Benz employs such a system on its three U.S. diesel offerings – the ML320, R320 and GL320 – but consumers may have to alter their maintenance schedules to keep their clean diesels running.
According to Automotive News, Mercedes’ family of diesel vehicles must return to a Mercedes dealership every 10,000 miles in order to maintain the proper level of urea fluid — AdBlue in Mercedes-talk. If the AdBlue solution falls below a critical point, the car’s onboard computer will prevent the vehicle from starting, leaving the driver stranded.
Drivers will be warned via a dashboard indicator once the AdBlue level hits one gallon, but if the warnings are ignored, the vehicle will be rendered useless. “It will count down, and if you ignore all those warnings, then it won’t start,” Dan Barile, a Mercedes-Benz USA spokesman, told Automotive News.
Moreover, filling the tank with water in a pinch won’t help the situation. The car’s urea system can detect when the real thing isn’t being used, and still won’t start. And if the level gets to the critical point where the vehicle won’t start, a full two gallons is required to reset the system.
But with 7-gallon urea tanks – 8.5 gallons in the R 320 – drivers should be covered for at least 10,000 miles. However, AdBlue is still rather costly – about the same per gallon as diesel – but shouldn’t really be a concern to anyone shopping the Mercedes brand.
So while clean diesels aren’t exactly as maintenance free as gas engines, they don’t beg for attention either. And with fuel economy improvements in the 20 to 30 percent range, we’re sure buyers can get over the maintenance schedule – granted they can also get past the diesel’s dated stereotype.
