BlueTEC: Top Luxury, No Sacrifice

We are driving a two-lane stretch of scenic highway through the Green Mountain National Forest in Vermont. This state is very green - both literally and politically - and is noted as an early adopter of the stringent California Air Resources Board (CARB) emissions regulations that put a halt to the sale of diesel cars in five of our 50 states. That fact makes this drive all the more remarkable because we are behind the wheel of a 2009 Mercedes Benz BlueTEC diesel that's so clean, it can now be sold in all states nationwide, including Vermont.

More remarkable yet is the fact that the vehicle we are piloting isn't a small commuter car or an urban shuttle, but rather a large, seven passenger luxury SUV that weighs in at more than 2-1/2 tons and can tow up to 7,500 pounds. The Mercedes Benz GL320 BlueTEC may be a heavyweight but thanks to modern clean diesel technology, it delivers fuel economy on par with a compact SUV along with exceptionally low tailpipe emissions.

Mercedes is offering the 320 BlueTEC clean diesel in all three of its large platform SUVs for 2009. In addition to the E320 sedan, the engine is now available in the redesigned ML320 five passenger SUV, R320 six passenger crossover style SUV, and the aforementioned GL320 seven passenger SUV. EPA fuel economy numbers for the big GL320 are 17 mpg city and 23 mpg on the highway cycle while the ML320 and R320 go one better with 18 mpg city and 24 mpg highway. Those numbers are with the new 2008 test procedure and we were able to do considerably better. Vermont's picturesque back roads are not particularly conducive to high fuel economy numbers, with numerous small towns and speed zones that impair steady cruise speeds. Still, with a conservative driving style we were able to maintain an average fuel economy in the 28-29 mpg range on the vehicle's fuel computer with little effort.

Diesel engines are on average 30 percent more fuel efficient than their gasoline fueled counterparts. The 320 BlueTEC is 3.2-liter double overhead cam (DOHC) aluminum V-6 that utilizes a variable geometry VNT turbocharger and Bosch CDI electronic fuel injection to coax maximum power from its relatively small displacement. Power output is rated at 210 horsepower at 3,800 rpm and an impressive 398 lbs-ft of torque between 1,600 and 2,400 rpm. With nearly 400 lbs-ft of torque at the ready, all three of these BlueTEC diesels never feel underpowered. A diesel's high torque is very satisfying in every phase of driving and Mercedes' seven speed automatic transmission does a great job of optimizing shift points to stay in that fat torque curve.

Essentially, the 320 BlueTEC provides four cylinder fuel economy with V-8 performance. Mercedes estimates the heavier GL320 will accelerate from 0-60 mph in 9.1-seconds, the R320 in 8.6 seconds, and the ML320 in 8 seconds flat. Despite their relative bulk, these vehicles all actually feel quicker than that thanks to the abundant torque. We also expect Mercedes is being rather conservative with its estimates and that actual testing will offer lower numbers yet.

BlueTEC incorporates a sophisticated exhaust aftertreatment system that utilizes AdBlue urea injection to transform nitrogen oxides into non-polluting nitrogen and water. Mercedes' BlueTEC 320 exhaust system has an oxidation catalyst, AdBlue injection to produce ammonia that will convert NOx, a diesel particulate filter, and a NOx storage catalyst. The AdBlue tank can is refilled through a port below the aft cargo floor and offers a 10,000 mile range. The consumer should never need to mess with AdBlue since the dealer will top it off at regular service intervals. If by chance the tank does need replenishing, a small AdBlue refill will be available. The system alerts a driver when the tank is low. If it runs out the computer will allow the vehicle to start 20 times before AdBlue is refilled.

We covered hundreds of miles in the trio of Mercedes BlueTEC clean diesel SUVs and our first impressions are more than favorable. As expected, Mercedes' quality and luxurious appointments are first rate. Green Car looks forward to a more in-depth review of the production BlueTEC clean diesel SUVs soon. Advanced technology, while seldom inexpensive, means you can drive an SUV and hold your head up high, even in Vermont.