Mercedes-Benz M-Class, R-Class and GL-Class CDI models
Mercedes-Benz M-Class, R-Class and GL-Class CDI models. Click image to enlarge
Manufacturer’s web site
Mercedes-Benz Canada

Review and photos by Bob McHugh

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2009 Mercedes-Benz BlueTec diesel models

Manchester Village, Vermont – The Mercedes-Benz E 320 BlueTec diesel sedan that I drove last year was my personal “Car of the Year”. At the time, its common-rail turbo V6 was the cleanest diesel on the market, and Mercedes was promising a new “AdBlue” injection module that would make it as clean as a state-of-the-art gasoline engine.

Well, AdBlue has arrived! Later this year Mercedes will sell three utility vehicles with BlueTec diesel engines and the AdBlue system. The BlueTec trio are the ML 320, GL 320 and the R320 and they will be the first diesel passenger vehicles to meet California’s ultra-strict emission standards. And this also means they can be sold in all 50 US States.

Bluetech AdBlue fill point
Bluetech fuel filler
BlueTech AdBlue fill point (top); BlueTech fuel filler. Click image to enlarge

A diesel engine actually produces less carbon monoxide and carbon dioxide than a gasoline engine. On the other hand, particulate emissions (soot) are an issue and its higher combustion pressures and temperatures cause it to generate more nitrogen oxides.

Advanced technologies in a BlueTec diesel engine allow it to have a more complete combustion process plus more after-treatment devices are used in its exhaust system. A particulate filter traps soot and an oxidation catalyst deals with leftover hydrocarbons.

In addition, the new AdBlue system injects a urea solution into the exhaust gas stream. This releases ammonia, of which 80 per cent is reduced to form harmless nitrogen and water by a downstream SCR converter.

The AdBlue urea solution is stored in tank under the cargo floor and fed to a metering module by a pump. The average consumption of AdBlue is around 0.1 litres per 100 kilometres and the tank is large enough so that it only needs to be refilled at a dealership during regular service intervals (about every 20,000 km).

The tank location takes the space in the trunk normally occupied by the spare wheel. Mercedes has solved this issue by fitting run-flat tires on these BlueTec vehicles and dispensing with a spare wheel.

Mercedes-Benz GL 320 CDI
2009 Mercedes-Benz R 320
Mercedes-Benz GL 320 CDI (top); 2009 Mercedes-Benz R 320 (bottom photo by Grant Yoxon). Click image to enlarge

The 3.0-litre V6 BlueTec diesel engine can produce a staggering 400 lb-ft of torque at just 1600 rpm. That’s superb pulling power, so these vehicles are really well suited to towing duties. Fuel economy and the full-tank driving range are excellent and slightly better than the previous generation V6 diesel.

Mercedes claims a city fuel rating of 11.3 L/100 km for both the ML and R and 11.5 L/100 km for the GL. Highway consumption is expected to be 8.3 L/100 km for both the ML and GL and 8.2 L/100 km for the R.

The ’09 standard equipment list in the ML, R and GL-Class has also been expanded. They now include the unique, preventive occupant protection system Pre-Safe and Neck-Pro head restraints, as well as a new, Mercedes-Benz developed telematic system with improved user friendliness and numerous additional functions.

Appearance wise, the ML’s front end gets a new-look bumper and headlamps with a pronounced step in the lower edge. A larger, lower-set grille has three wide louvers. New-look projection-beam headlamps have chrome edging. Roof rails are now standard and the side mirrors are larger.

Mercedes-Benz GL 320 CDI
2009 Mercedes-Benz ML 320
Mercedes-Benz GL 320 CDI (top); 2009 Mercedes-Benz ML 320 (bottom photo by Grant Yoxon). Click image to enlarge

The GL comes with new generation audio and communications systems with standard Bluetooth connectivity and an SD card slot. The GL 320 and GL 450 get new wheels, re-designed mirrors and steering wheel. New options include a 610 watt Harman-Kardon sound system and a rear seat entertainment system.

A minor appearance change to the R-Class is a black grille with chrome highlights. Inside it also gets the new generation audio and communications with media interface and the optional Harman-Kardon sound system, etc. A trailer hitch with 3,500 lbs. towing capacity is new and the R 550 has been deleted for 2009.

Seventy years ago, Mercedes-Benz was the first manufacturer to use the combustion principle pioneered by Rudolf Diesel in a passenger car engine. It has also pioneered the introduction of common-rail direct fuel injection in combination with four-valve technology in modern diesel engines.

It’s no coincidence that the introduction of these vehicles coincides with the introduction of low-sulphur diesel fuel in North America. As that computer geek adage goes, “garbage in, garbage out.”

By the way, that same adage also applies to our gasoline, if BC and Quebec are serious about matching California’s emissions reduction timetable.

So, to sum things up, the AdBlue injection system makes the new M 320 BlueTec, R 320 BlueTec and GL 320 BlueTec the cleanest diesel SUVs in the world!

Manufacturer’s web site
Mercedes-Benz Canada

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