Noise? Smoke? Soot? Forget it! The 3.0L TDI V6 under the Audi A8 L’s hood emits almost none of the above.

Noise? Smoke? Soot? Forget it! The 3.0L TDI V6 under the Audi A8 L’s hood emits almost none of the above. Start it up: barely a peep. Stand at the rear: all’s quiet at the tailpipes. Keep up with flowing traffic? Noiseless. Engage a tidal-wave of luxury-thrust to fly by an 18-wheeler on the highway? The subtle roar from the engine sounds like its coming from somewhere off in the distance as you surge gracefully by.

If memory serves me, the A8 L’s TDI engine is even quieter, more of the time, than the now-retired 4.2L V8 which powered the last A8 I drove a few years back. And it hauls along almost just as well. All of that in a machine that consumes pavement like a V8, and consumes fuel like a four-cylinder. Literally.

Sounds pretty win-win, yes? This is diesel power today: surprisingly good performance, incredible refinement, and even more incredible mileage. All said, the concept of diesel-powered cars not being everywhere flies so far over my head that it needs a passport.

The contractor who recently worked on my new bathroom shone some light onto the reason for the above. There was a Dodge Ram EcoDiesel in my driveway that week, and he was measuring the box to see if he could fit drywall and plywood and contractor things inside. But contractor guy said he’d never buy a diesel.

“We had one years ago. A Rabbit. My wife hated it. It stank and it was smoky and didn’t like starting in the cold. I couldn’t do a diesel” he explained.

Things have changed, contractor guy.

“How long ago was that”? I asked.

“Oh gosh, we got rid of it in probably 99. But it was an 87, or 88, I think”.

Things have changed, contractor guy.

Case in point? The A8 L is one of the most luxurious cars on the planet, and opting for its diesel engine takes nothing away from the experience. In fact, the TDI engine is the perfect powerplant to complement the A8 L’s underlying character.

Perfect, because the A8 L turns in such a relaxed driving experience with its massaging seats and air suspension and dual-pane, acoustically-laminated glass and crystal-freaking-clear Bang and Olufsen stereo system that you’ll be at ease. Peaceful. Not in a rush. Laid back. That means you’ll apply the throttle gently, let the monster low-end torque glide you up to speed without breaking 1,300 revs in each of the eight gears, wonder how a transmission can shift so smoothly and quickly, and get silly-good fuel mileage in the process.

On winter rubber, using the Quattro system often and vigorously, I did 8.8 L/100 km overall. That’s not bad for a big, fast, high-tech luxury spa on wheels. Highway cruising in no particular rush saw consumption drop to just 7 L/100 km. I’ve literally put more fuel through a four-cylinder Honda Accord – and the A8 L is twice the size, has numerous times as much torque, and drives all fours.

But would the promise of very refined, very efficient performance change the contractor-guy mindset on diesel power? Maybe so, maybe no – as there are other challenges in getting diesel to become more widely accepted.

For one, gas prices are plummeting delightfully. That’s not great if you’re dealing in diesel. Further, there’s the horsepower thing. The tester’s output of this figure was 240: not an impressive number to a horsepower-obsessed North American shopper. Spouting horsepower figures is like flexing your biceps when someone asks to see your muscles: it’s the go-to measurement of all things manly and powerful and testosterony. With a diesel engine, the important and impressive figure is torque – but the average shopper doesn’t care about torque.

Maybe they should start? The A8 L’s 3-litre turbodiesel mill churns up 406 lb-ft of the stuff from just off of idle. Even the biggest gasoline V8 engines barely match that figure. Hammer it from a dig, and the big torque blasts the A8 L up to speed as if it’s just been rear-ended by a speeding dump truck. With Quattro AWD eliminating wheelspin and all that thrust, right away, the A8 L gets up and goes, right now, when requested. Torque is great stuff for both effortless light-throttle acceleration, and getting off the line something fierce.

And all in the lap of luxury.

On top of its gorgeous open-pore wood, extremely comfortable massaging seats, privacy screens and ambient mood lighting and televisions and central command consoles in the front and rear, the tester rode an airbag suspension system that sees it virtually hover over rough roads. There’s abundant legroom in front and rear, and you can lounge about in the reclining, massaging, heated and ventilated rear seats, send navigation destinations up front for your driver, deploy privacy screens so nobody peeps in on your luxury rear-seat activities, and take in a movie on your own TV screen. Or, play some Clapton on the mega-watt stereo system, complete with pop-up tweeters that make your writer not even care if the thing plays music at all.

That stereo is a $7,000 option. Many more fitted to the tester, which had an optional equipment cost totaling the MSRP of a nice Lexus. All said, the tester, as tested, would relieve its owner of about $137,000.

There’s plenty contributing to that price tag. First, A8 L is a handsome looker: massive in size and restrained in the use of chrome and glitz and shouty design touches. You needn’t be wearing a suit, sporting a set of Ray-Bans and a Bluetooth earpiece and whisking dignitaries out of hot-zones to look like you belong in this machine. The consistently lavish ride quality helps towards the price tag, too.

But in all, it’s got to be the cabin that pulls its weight hardest towards the lofty sticker. Layer upon layer of texture and detail and colour play off of and intersect with one another, every inch of the thing is masterfully detailed, and you couldn’t find a cheap piece of trim if you tried. It’s an absolutely rich-looking cabin.

And front or back seat, it’s the world-class treatment. The atmosphere expertly combines luxury and tech, sitting between the S-Class and 7 Series with a nice, even-keel blend of both attributes, and none overwhelming the other. Notably, much of the central control functions are mounted on the centre console, not the dash, which contributes to a clean and un-cluttered view outward. If you’re indeed driving, you can access hundreds of functions via the dial-controlled MMI system, fiddle with the pedestrian-detecting night-vision camera system, the Drive Select system or the scribble pad, which lets you write inputs into the system with your fingertip.

The A8 L can be calibrated into several setups, depending on what you’re up to. The comfort mode is light, loose and floaty, and sees the steering capable of one-finger manipulation, the body undulating gently on the wheels as bumps pass beneath, and the transmission encouraging low-rpm operation for more refinement and better mileage. Conversely, the Dynamic mode turns up the urgency, stiffens up the steering and suspension, and dials the AWD system’s differential into a friskier, more tail-happy setting.

Conversely, the Dynamic mode turns up the urgency, stiffens up the steering and suspension, and dials the AWD system’s differential into a friskier, more tail-happy setting.

A few notes relating to winter driving. The Quattro system is truly seamless: leave the differential in its Comfort setting, and keeping the rear wheels following the front ones tightly is the priority. Even as surfaces with varying traction pass beneath, light to moderate throttle sees the A8 L stays true to the line selected with no squirming or fussing felt from under the car. Engage a sportier setting and some more weight to your right foot, and you can feel the system hunt for traction, trying each wheel and re-strategizing its power between and across the axles to keep you moving.

Choose to slide and slip around in the snow, and the stability control system leaves you alone for all but the biggest slides, or until you panic, as detected through sudden steering, throttle-lift or braking events. Rather than put the throttle on lock-down and clicking away at the brakes when a slipping wheel is detected, the A8 prefers to first work with the driver through instant re-calibration of the AWD system’s power split for a more involving, entertaining experience that enthusiasts will appreciate. I’m not certain how many folks driving an A8 L are concerned about amusement by low-traction situations, but for those that are, slipping and sliding about in a machine this big and long and comfortable is a total hoot.

The ABS system’s actions are heard and felt more than your writer expected, though it’s highly effective too, and deals with emergency brake-and-evade manoeuvres over split-traction surfaces with minimal shifting and slipping of the car on its intended line. The front stays true to where it’s pointed, with the rear sliding a little, in extreme manoeuvres. Easily manageable.

All said? Depending on the mode selected, the A8 L is as planted and stable and confident, or as frisky and amusing, as you’d care for it to be. It’s expertly calibrated for a unique feel in each of its modes, in the snow.

Also notable were the LED headlamps, which flood the road ahead vividly with crisp light that penetrates into the tree-line beside two-lane highways, and the night-vision camera system, which can draw you attention to warm objects with legs, like people and moose, that you might not see up the road in the dark. Further, the turning circle is surprisingly tight for a machine of such length and girth.

As it tends to go at this price point, complaints are minimal. Your writer occasionally wished for a heavier steering feel on winding highways to better lock the A8 L onto its line, and the MMI system takes a bit of learning before you’ll be clicking and dialling through its functions like second nature.

If I’ve ever driven a better car than the Audi A8 L TDI to prove that today’s diesel powered rides are refined, smooth, quiet, odourless and very pleasing in the seat of your pants when you stomp the throttle, I don’t know what it is. Consider the A8 L TDI a flagship priority test-drive if excellent mileage, pleasing power delivery, heaps of lavish space, and a world class level of comfort and confidence, even in lousy weather, are on your wish-list.

Warranty:
4 years/80,000 km; 4 years/80,000 km powertrain; 12 years/unlimited distance corrosion perforation; 4 years/unlimited distance 24-hour roadside assistance

Competitors:
BMW 7-Series
Infiniti Q70
Mercedes S-Class

Specifications

Model Tested 2015 Audi A8 L TDI Quattro   Destination Fee $2,095
Base Price $96,700   Price as Tested $137,245
A/C Tax $100  
Optional Equipment
Bang and Olufsen Sound ($7,000), Night Vision ($2,500), Rear Seat Entertainment ($3,300), Driver Assistant Package ($3,900), Rear Seat Comfort Package ($4,250), Multicontour and Ventilation Package ($2,100), Luxury Package ($3,900), Sport Package ($4,400), Full Leather Package ($7,000)