2014 Audi A8L TDI Diesel

2014 Audi A8L TDI Diesel 2014 Audi A8L TDI Diesel
Instrumented Test TESTED

Anyone who has kept tabs on the 24 Hours of Le Mans the past few years knows Audi has a pretty good handle on diesel technology—better than most other automakers, in fact. And now the company has brought its compression-ignition expertise to bear on its largest sedan, gifting it the fuel-pump thriftiness of a smaller car while offering all the trappings one expects when spending enough coin to buy three family sedans.

Indeed, the A8L is Audi’s premier four-door—the L is for “long wheelbase”—and the power choices now include the corporate 3.0-liter turbo-diesel. It takes its place in the A8L pricing hierarchy just above the $79,695 A8L 3.0T, although if you add a few extras, such as the $6300 Bang & Olufsen audio, it isn’t long before you’re close to 100 large. That was true of our test car, which rang in at $99,445.

The 3.0 turbo-diesel makes plenty of torque—no surprise there—although if your objective is pavement-scorching acceleration, this might not be the right luxo sled for you. Still, the diesel overcomes inertia with authority, and reaching 60 mph from rest in 6.4 seconds isn’t exactly slow for a vehicle that pegs the scales at 4585 pounds. Thank goodness for the weight-saving aluminum-intensive structure, eh? But the turbo-diesel isn’t quick, either. For contrast, an A8L with the 3.0-liter gas turbo V-6 (333 horsepower, 325 lb-ft) was a second quicker to benchmark speed, and the A8 stable also has the short-wheelbase, 3.6-second S8 and the 3.9-second A8L 4.0T. So CEO types with a speed addiction can still get a fix.

MPG! LOL?

However, diesel propulsion is more about mpg than mph, and on that score sheet, the TDI gets better marks than anything else in the A8L lineup. The EPA ballparks 24 mpg city and 36 highway for the TDI versus 18/28 for the 3.0 gas engine. The substantial spread between cars was borne out in our testing, as we logged 32 mpg with the TDI and 21 with the 3.0T.

Then again, there is a point to be made that the affluent likely care least about fuel economy among car buyers. At minimum, the TDI’s torque is a welcome companion in day-to-day dicing and is further sweetened by the smooth action of the eight-speed Tiptronic automatic. In Sport mode, the shift paddles deliver reasonably prompt responses, and the big sedan delivers the same eager handling—albeit tempered by mass—as does the rest of the A8 line.

We were even more impressed with the TDI’s braking: 149 feet from 70 mph is sports-car territory, and a driver can count on duplicating that kind of stopping as often as he likes without provoking fade. If there’s any dynamic flaw, it’s the power steering, a traditional hydraulic unit that’s quick, accurate, and tactile but gets uncomfortably heavy in vigorous cornering at low speeds. We take comfort in the fact that very few owners will find themselves in this sort of situation.

That debit aside, the A8L TDI satisfies like its long-wheelbase stablemates. It is big, elegant, and beautifully appointed and boasts enough rear cabin room to host the local Illuminati meeting. To the other big A8s, though, it adds exceptional fuel economy, proving once again Audi’s ability to calculate winning formulas on the racetrack and off.