The Q7’s 3.0-liter TDI diesel V-6 is a winner. It’s so quiet, so smooth, and so powerful. Well, so torquey, I guess I should say, since it has 406 lb-ft, compared with 266 lb-ft for the 3.6-liter gasoline V-6 offered in the base Q7. Cruising at 80 mph on the freeway is effortless, and if you gun it to 90 mph or higher while you’re passing, it’s as if the engine is not even exerting itself. The powertrain is also very smooth and refined at slower, around-town speeds. It’s a very tractable engine, well-mated to its six-speed automatic. Audi estimates a 0-to-60-mph time of 8.5 seconds (not bad for a 5512-pound, 16.7-foot-long crossover) and a range of up to 600 miles in freeway driving, based on the highway EPA rating of 25 mpg and the 26.4-gallon fuel tank.