The story here is mileage. And it couldn’t come at a better time, as German automakers face an uphill struggle to change American perceptions about diesel fuel and engines. Due to tax incentives in much of Europe, diesel has been the cheapest fuel for decades there, and that has resulted in German engineers’ extensive development and refinement of the sparkless internal combustion engine. No longer smoky, clattery beasts of burden suitable only for trucks, in Europe diesels grace everything from S-Class Benzes to BMW’s new 7 Series Q ship. They are eager to spread this technology to America, but higher prices for complex engines on top of higher prices for diesel fuel in America are considerable obstacles.
Enter massive PR efforts like the Mileage Marathon. How does a best average of 29.40 mpg from the 5,000-plus-pound Q7 SUV sound? That includes crossing the rocky mountains (nearly 11,000-feet mountain passes), bumper-to-bumper slogging through Manhattan, and power-sapping 86-degree weather approaching Vegas.
But the Q7 is actually the worst mileage news. The new Q5 SUV with the same 3.0-liter TDI V-6 (240 hp, 369 pound-feet) rang in with a best of 37.94 mpg. The fleet new A4, again with the 3.0 TDI (369 pound-feet has got to be fun in this tidy sedan), netted up to 44.38 mpg. And the well-received A3, with a 2.0-liter TDI shared with the Volkswagen Jetta TDI, soared up to 47.04 mpg.
Last but not least, Audi touts this quartet of diesels as the cleanest in the world. New technology in the form of particulate filters and SCR (selective catalytic reduction) have eliminated the soot from diesel exhaust pipes, as well as turning much of the toxic nitrogen oxide into water vapor and harmless nitrogen gas, respectively. Audi apparently has gone the extra emissions mile with its new-for-’09, 50-state-compliant TDI engines, which already comply “with the Euro 6 standard not scheduled to come into force until 2014.”
Would you consider buying a new clean diesel from BMW (3 Series, X5), Mercedes (E320 BlueTEC, ML320 BlueTEC, R320 BlueTEC, GL320 BlueTEC), Audi, or VW (Jetta TDI clean diesel)? Are these mileage marathons inflated hype from PR departments, or do they strike you as legit proof of diesel’s superior economy? We know that our loquacious blog commenter, Ed, is all about the diesel. And I claim my own bias in favor of the diesel’s efficiency, longevity, and megatorque. What say you readers, enthusiasts, and automotive consumers?--Colin Mathews