x Abu Dhabi, UAEThursday 20 July 2017

Road Test: Audi sparks fuel-sipping war between A8 Hybrid and diesel

With comparable pricing, Audi has set up a sales battle between its diesel and new, equally-as-efficient Hybrid, with the choice coming down to personal preference.

Here's an interesting question, at least here in North America. Given a choice between equally sipping technologies at virtually the same price, which will consumers — in this case, well-heeled consumers — opt for; the media darling or the dark horse? More specifically, I have been long awaiting a showdown between hybrid (that would, in North America and China, be the media darling) and diesel (much favoured in Europe and many other places around the globe) technology. And although there are plenty of hybrids and diesels out there, no single model has offered both powertrains to allow direct comparison.

Audi will soon be changing all that.

Audi's A8 3.0L TDI is, of course, a well-documented leader in diesel technology. Fast, smooth, luxurious and remarkably frugal, it's a mainstay of the new A8's line-up in Europe. It is, however, being joined by an all-new, almost-as-parsimonious, version of Audi's top-of-the-line saloon, the A8 Hybrid. And what makes this all so interesting, at least to me, is that though their powertrains are completely different — one is a turbocharged 3.0L V6 diesel while the other is powered by a combination of Audi's 2.0 TFSI four and an electric motor — they share some key similarities. Both cost in the €75,000 (Dh360,272) range and, while the diesel is particularly clean and frugal — 169 grams of CO emitted per kilometre and 6.4L/100km overall — the new 2013 Hybrid's 147g/km and 6.3L/100km are equally impressive. The choice, therefore, will be a combination of personal prejudice and/or any perceived difference in comportment.

One possible hurdle for Audi to overcome will be the fact that the Hybrid sports but four cylinders. Yes, four is generally more frugal than six or eight and, yes, the Hybrid badge on the rear boot lid adds the legitimacy of an electric motor driving the front wheels and a big graphite-cathode lithium-ion battery in the boot. Nonetheless, the new A8's basic powerplant is still the same 2.0L TFSI turbo four cylinder that can be found in all manner of downmarket Audis, not to mention a slew of even more pedestrian Volkswagens.

So, the big question is, what does the environmentally conscious banker give up in his or her quest for both hedonistic luxury and fuel-sipping parsimony?

Not too much, if my short drive around Audi's spiritual home of Neckarsulm, Germany, is any indication. With only four pistons combusting, the Hybrid boasts 245hp - middling, anyway you judge it. But, sporting a turbocharger and a transmission-mounted 40-kilowatt electric motor for added thrust, there's an almost diesel-like 480Nm of torque available as low as 1,500rpm (by way of comparison, the up-level version of the 3.0 TDI boasts 247hp and 550Nm of torque).

Riding that wave of torque, there's very little indication that the Hybrid is anything other than yet another fully hedonistic luxury saloon. Even from low revs, acceleration feels muscular (acceleration to 100kph takes 7.7 seconds, little more than a second slower than the most powerful version of Audi's 3.0 TDI) and, thanks to the engine's relatively low revs and some excellent noise, vibration and harshness management from the standard active noise control system, none of the cacophony usually accompanying high-revving four-bangers intrudes on the sybaritic (of which, like in all A8s, there is much) experience.

Only at the upper reaches of its rev band (and exactly what rpm I am referring to is a mystery as Audi has replaced the traditional tachometer with a more hybrid-orientated "per cent power" meter) does the diminutive powertrain feel strained, and only when asking for more maximum warp speed.

Still, you can occasionally feel a few vibrations through the throttle pedal, when the eight-speed automatic transmission — obviously calibrated for fuel economy — tries to keep its torque converter locked when accelerating at low revs (usually during a mild passing manoeuvre). Then, the combination of high load and low rpm sends a little four-cylinder tingle through the driveline. It's a minor thing, something even princess-and-the-pea types might miss were they not in their hypercritical autojournalistic mode.

However, there are some compromises if you want an A8 to achieve the same "real-world" 8.6L/100km I averaged during my 200km stint in the Hybrid. The first is that the quattro all-wheel-drive system for which Audi is justifiably famous is not available with the hybrid powertrain.

Also, although the 1.3kWh battery (good for three kilometres of electric-only motoring, if you have a delicate throttle foot) weighs only 38kg, it takes up quite a bit of space in the boot, with a pronounced hump precluding the loading of a full-sized golf bag. Part of its girth is a nifty cooling system that force feeds the batteries atmospheric air as well as some from the air conditioning system to ensure all those lithium-ions never exceed 42°C.

Lastly, the A8, like all hybrids, uses regenerative braking — essentially reversing the polarity of the electric motor — to recharge the battery while stop-and-going around town. This electrical retardation can be a little over-sensitive when braking at slow speeds. No matter how gingerly the brake pedal is massaged, there's a little burp as the electric brakes kick in. It's not apparent at high speeds and most owners should quickly acclimatise, but other car makers with more experience with hybrids — Toyota, for instance — have managed to attenuate the problem.

And, finally, just to confuse things even more, it turns out that Audi actually offers two different versions of its TDI, the other an even more frugal version of the 3.0L with 201hp that boasts an even more impressive 6.0L/100km overall fuel economy in the EU cycle (its 7.9-second 0 to 100kph time is almost bang on that of the Hybrid). So to reiterate, Audi has three A8s with overall fuel economy in the sixes — 6.6, 6.3 and 6.0 — with the Hybrid flanked by the two diesels.

Although all three won't be offered in every market - including this one - some markets (Germany, for instance) will sell all of them. That's almost a profligate embarrassment of riches for such a narrowly niched automobile. I, for one, am very interested to see which proves the most popular. And I am pretty sure that I won't be the only one awaiting your decision.

Price, base / as tested N/A

Engine 2.0L turbocharged inline four cylinder with electric motor

Gearbox eight-speed automatic

Power 248hp (combined)

Torque 480Nm @ 1,700rpm

Fuel economy, combined 6.3L/100km