The ancient Mercedes-Benz 300SD puffing along in the right lane of the freeway, belching smoke, cruising sedately at the posted speed limit, perfectly underscored why my 2014 Audi A6 3.0 TDI test car had large “Clean Diesel TDI” lettering emblazoned upon its front doors. Diesel is different today.
Back in the 1980s, when the smoking but durable Benz was built, and when General Motors produced horribly inept diesel-powered V-6 and V-8 engines that turned an entire generation of car buyers off to the technology, diesel engines were smelly, smoky, clattering weaklings. Today’s diesel engines meet strict emissions regulations, even those in the ultra-green state of California, and they’ve got impressive power. The key to appreciating a diesel engine beyond fuel economy numbers, though, is to understand why torque is just is as important as horsepower to your daily driving.
Most people focus on horsepower as a measure of potential performance, but torque is what you feel from behind the wheel when you’re accelerating, and is a significant contributor to that sense of gathering momentum and thrust when you mash the accelerator. Those old diesel V-8 engines installed in Cadillacs and Mercedes-Benzes struggled to make 200 pound-feet of the stuff, and their horsepower ratings didn’t help, hovering right around the 120-hp mark.
This Audi? It’s cranking double the amount of horsepower and torque through all four of the A6’s wheels, and gets to 60 mph in 5.5 seconds while returning an EPA-estimated 29 mpg in combined driving. Sound good? Keep reading.