Audi A8 TDI, for the eco-minded mogul

When Rudolf Diesel fell from the mail steamship Dresden into the North Sea in 1913, his engine design had not yet achieved its eventual success, and his company was out of cash.

The purposeful grumble speaks of muscle.

In the century since Diesel’s death, however, advancing technology has polished the engineer’s onetime sluggish and smoky power plant into a model citizen. It was this reality that motivated Audi to go all-in on diesel when it announced last fall that it would bring diesel power to its mid-and high-end sedans and crossovers in 2013.

The first of the new crop to arrive in North America is the A8 TDI, a fuel-sipping version of the company’s flagship. For refinement, power and efficiency, it is difficult to conceive of a luxury sedan to top it, with its combination of extravagant wood and leather appointments, 36mpg highway fuel-economy rating, 6.4-second zero-to-60mph acceleration and all-wheel-drive security. (Its natural foil, the Mercedes-Benz S350 BlueTec, feels woefully out of date – though that may be addressed in the S-Class’s redesign.)

Not long ago, such a combination of qualities would have been considered impossible. Today, it is just another modern miracle, like using an iPad to programme the DVR to record Game of Thrones while awaiting your delayed flight in the departure lounge.

Mercedes’ S-Class has long been the golden, if somewhat stodgy, standard among premium full-size sedans, with the BMW 7 Series fulfilling the role of the sporty alternative, while Audi’s A8 languished, overlooked for years. But Audi has quietly built Quattro-like traction in the prestige sedan market, thanks in part to differentiators like its proprietary all-wheel-drive system, but also to icy-cool styling and a generous spread of modern miracles like signature LED lighting, satellite photo navigation (a driver sees actual photographs of the preprogrammed destination) and civilised, powerful, fuel-saving diesel engines.

From the driver’s seat of the A8 TDI, the exhaust note, responsiveness and thrust make it entirely possible to mistake the car for a gasoline-burner. Outside, a diesel’s telltale gurgle is noticeable, but only in the way cognoscenti would discern, say, a V8 engine from a straight-six. Yes, you can tell from the curb, but the purposeful grumble speaks of muscle. 

For shoppers worried about the relative difficulty of finding diesel fuel in a gasoline-centric land such as the US, there’s an app for that. When the car gets low on fuel, the navigation system automatically locates any or all nearby diesel stations and offers to plot a route.

The engine’s mammoth 406 pound-feet of torque punts the A8 over highway and surface street with ease, as the 8-speed automatic transmission slips imperceptibly through the gears. With a prudent foot on the throttle, the car proceeds with grace. Floor it, and the A8 TDI positively leaps forward – if not as lustily as its 520hp S8 stablemate – abetting efforts to squeeze the long-wheelbase saloon into a tight pocket of traffic.

Just as the car’s lines minimise the A8’s visual mass, so too do the suspension and steering create the illusion of a smaller car, particularly on winding roads. The A8’s boulevard ride is unimpeachable, but making a big car do the twist is a challenge, one which Audi has clearly surmounted. Steering boost, suspension stiffness and throttle response are customisable through Audi’s Drive Select system. In “Dynamic”, the sportiest preset setting, some drivers might find the steering effort excessive. For them there is a “Comfort” configuration, which provides more assistance while retaining the excellent feel communicated in Dynamic mode. Drivers accustomed to Lexus levels of cushiness may choose to set all Drive Select parameters to Comfort and be done with the function forever.

That this level of adaptability exists in a car weighing 4,564lbs helps to justify its nearly six-figure as-tested price. And if the owner cares little about the cost savings of fewer fill-ups, surely the diminished frequency of those stops won’t go unappreciated.

Vital stats: 2014 Audi A8 L TDI

  • Base price: $83,395, inclusive of $895 destination charge
  • As tested: $99,445
  • EPA fuel economy: 24mpg city, 36mpg highway
  • Powertrain: 240-hp, 3-litre turbodiesel V6 engine, 8-speed Tiptronic automatic transmission, Quattro all-wheel drive
  • Standard equipment: GPS navigation with satellite imagery, Audi Connect multimedia system, Bluetooth connectivity, four-zone automatic climate control, power trunk lid, power sun shades
  • Major options: Bang & Olufsen sound system, LED headlights, heated/cooled massaging seats, adaptive cruise control, automatic high beams, panoramic sunroof, 20in aluminium wheels