German engineer Rudolph Diesel surely would be proud to see how far his innovation has come. It was in 1894 when he came up with a variation of the piston engine, one that would use compressed air to ignite the fuel.
Yes, it won the "Grand Prix'' Award at the 1900 World Expo in Paris, but it was awfully big and dirty and bulky and best for work-horse, low speed chores. Early Mercedes-Benz folks first put it into trucks, then refined it for automotive usage by the 1930s.
Still, a little dirty, noisy, smelly. I had a diesel in my old '80s VW Rabbit and, while I loved to boast of 50 mpg on the highway, it, too, was noisy and a tad smelly.
Now Mercedes has introduced its new Bluetec diesels to several models, including the R320 SUV, and it's time to rethink diesel one more time. Combined with ultralow-sulphur diesel fuel, the Bluetec diesel delivers the economy of a four-cylinder with the power of V-8, plus quiet, clean performance that stands up to any gasoline engine.
Remarkably, you won't know you're driving a diesel till you pull into the gas station and have to locate the (typically-yellow) diesel pump.
On the road, it's quiet enough to forget you are driving a V-6 diesel-powered vehicle. Only an attentive ear can detect the subdued diesel rattle.
There's plenty of power but not-so-brisk acceleration -- Mercedes says the BlueTEC diesel offers 30-50 percent more torque, or pulling power, than comparable gasoline engines. The 210-hp engine puts out 398 foot-pounds of torque. Zero to 60, though, takes nearly 9 seconds.
Mileage is 20 percent better, with the R320 capable of getting into the low 20s for combined city/highway driving. I managed around 20 mpg combined.
One caution, however: Diesel fuel these days is considerably higher than regular gasoline and that will factor into your fuel economy. At one station in Central Florida, I paid $4.76 a gallon, though that was some months ago.
Its seven speed tranny shifts through with ease, up and down, and handling was kept in check with the available Airmatic air suspension system.
The seven-passenger R-Class has plenty of other draws and, mostly, they pertain to the interior. A sunroof is standard this year, as are a new audio and navigation unit and new voice controls. It wasn't the easiest system to figure out in the short time I drove the R, but there was no manual in the vehicle to assist me,
Another new feature: All R-Class vehicles are equipped with all-wheel-drive for 2009.
It is minivan-like in many ways, yet there is a greater level of elegance, featuring leather seats, maple or walnut trim and 12-speaker Harman Kardon audio system. Another distinguishing difference between the R-Class and minivans: The rather large rear doors swing out, rather than slide and are a bit more cumbersome.
Fold the seats down and it delivers 85 cubic feet of cargo space -- quite decent, not quite minivan capacity.
All R-Class models get traction and stability control, brake assist and side curtain air bags for all three rows.
This is a fine people-hauler with the luxuries you expect from Mercedes. As for the diesel decision, well, half of the cars in Europe are diesel. And know that diesels continue to find their niche in the U.S., with one forecaster saying that diesel will account for 15 percent of cars and light trucks here by 2015.
The Bluetec burns cleaner fuel, is quieter and offers more pull per square inch. It may just change the way you think about diesels.