Audi A8 Hybrid 2012 Review - International

Audi A8 Hybrid

What we liked:
>> At least they’re having a go
>> Smooth transition between motors
>> A bit more economical

Not so much:
>> Battery gobbles the boot
>> No more economical than a diesel
>> Not the most energetic A8

Audi also thinks its A8 Hybrid needs to be cost effective, which is why it's putting its aluminium-framed A8 flagship into the fray with a four-cylinder engine where a big six or eight-pot would normally sit.

If the hybrid part is new to the Audi world, the engine certainly isn’t. A multiple Engine of the Year award winner, the 2.0-litre TFSI engine is turbocharged and boasts variable valve timing and direct fuel injection.

At its best, it’s clean, fast, smooth and flexible, but then it was never been designed for a 5.14-metre car. It’s an engine that’s seen Audi service in the A3, the Q3, the Q5, the A4, the A5, the TT and two generations of A6.

In the A8 Hybrid, where an automatic transmission’s torque converter would normally be, sits a disc-shaped electric motor. The other end of the equation is a huge battery pack taking up a large slice of the car's luggage capacity.

Together, the two hook up for a combined fuel economy figure of 6.3L/100km and a CO2 number of 147g/km.

PRICE AND EQUIPMENT

It will be built in two versions, with the short-wheelbase A8 Hybrid listing at €77,700 in Germany and the long-wheelbase (mainly developed for the Chinese market) €85,400. China will be the most important global market for the machine, though the LWB versions will arrive some months after Europe gets its SWB jobbies in June.

Audi tried to push the unique spec argument on us, but while it gets its own Metallic Arctic Silver paintwork and specific 19-inch wheels, the reality is that A8 buyers – even environmentally suckered ones – aren’t really about dodging luxury.

It comes standard with LED headlight, a BOSE sound system and a three-zone air conditioning system, but it doesn’t stop there.

It sounds counter-productive to have ambient lighting when you’re trying to save fuel, but that’s what it has; while your seats can have massage and ventilation functions and you can still put Bang & Olufsen surround sound in it. The satnav comes standard with the now-signature touchpad and the whole thing is a rolling WLAN wifi hotspot.

Clearly, that’s not going to move luxury owners fast enough when there are five metres of metal in the way, so it gets help. That starts by fiddling around with its own ancillaries -- Audi has dumped the mechanical drive belt for the usual array of pumps, because they’ve mostly been converted to electric drive.

There is an electric pump for the brake master cylinder, electric power steering and on-demand electric pumps for the oil and water. Basically, anything that needed crank-driven belt drive is now electric.

The permanent magnet, synchronous electric motor boasts 40kW and 210Nm of instant torque. Together, the two motors combine for 180kW of power and 480Nm. No, they don’t add up, but hybrid outputs just don’t work like that.

The electric motor is matched to a wet clutch pack that connects and disconnects it from the normal drive system which is through an eight-speed automatic transmission. Unlike the rest of the A8 range, the Hybrid only drives the front wheels.

The electric motor can flip from giving to taking, switching into generator mode to help rapid-charge the battery, too.

The back end of the deal is a 38kg lithium-ion battery pack that’s been slotted into the leading edge of the boot. Audi calls it a “crash safe” environment for the 72-cell unit, but more on that later…

That space is not just for a 1.3kWh battery, either, because it also houses the plumping for its cooling system, which normally sucks air out of the cabin or, when it needs more help, from the air conditioning system.

All of this lives within the established A8 space-frame aluminium chassis that weighs 231kg. Audi claims it’s 40 per cent lighter than an equivalent steel chassis, and the stretched chassis of the LWB version is 10kg heavier.

That it contrives to add another 1639kg on top of that (for an 1870kg kerb weight, if you’re too lazy to add it up) is a testament to both the luxury demanded at this end of the market and to what happens when you stick two powertrains in one car.

There are few immediate hints in the cabin that it’s different to the mainstream versions. Its standard interior trim level is extremely high and while few people ever leave an A8 in the stock format, the option list is extensive as well.

The materials used in the cabin drip luxury and style and the design and the razor-tight panel fit suggests quality everywhere you look.

The front seats have 12-way electric adjustment, but they’re just the start. Further upstream, you can pay more for the comfort sports seat, which adds 10 adjustable air cushions, ventilation (which passably supplants air conditioning up to about 27 degrees) and even a massage function.

The first real hint is the tiny button on the dash that allows you to run the A8 Hybrid as an electric car, which is said to be useful for coasting cleanly through Green Zones – though not the Baghdad kind.

The seven-inch display screen has picked up some additional work, too, because it’s now responsible for an energy flow meter to tell you which motor you’re using and whether you’re recharging the battery or draining it.

Audi has also replaced the standard tachometer with a power meter that has green and orange sections, plus an overboost area, to show you how efficiently you’re driving.

But the biggest packaging issue is behind you. The battery so effectively chomps into the boot space that it drops by a third from 510 litres to 335. But that's not the half of it – the sharply stepped shape that results makes the remaining space awkward to use. It’s as clear an indication as any that Audi is using this as a toe-in-the-water exercise rather than expecting it to be a boom segment.

Benz punched out its S-Class hybrid a couple of years ago to mixed reviews. More recently E-Class has come in for the same treatment.

Benz uses broadly similar technology, with a disc-shaped electric motor sitting between a conventional engine (a petrol V6, in the S400 H’s case) and the gearbox, though Benz found space for a much-smaller battery beneath the bonnet, so it doesn’t eat up the boot.

BMW shares the broad strokes of the Benz tech (they co-developed it), though it’s known to see hybrid drive as a means of boosting performance, rather than economy. This explains the 'Active' in its ActiveHybrid naming system for the 7 Series and even the X5 and X6 versions.

While they’re all called hybrids, they’re not all built for the same reasons and they’re not all aimed at the same audience.

That’s why the A8 is the only one with a four-cylinder petrol motor…

That’s the theory.

In reality, we found we could never cram enough charge into the thing to cover more than 1km or so, regardless of how reticent the right foot’s flexing muscles.

It’s very quiet in the electric mode, though, with its decibel readings dropping so low it almost got to loungeroom levels. It’s so quiet you can hear the front suspension moving (which is odd in itself) and its inherent shush is backed up by Active Noise Control, which broadcasts the “anti-phase” of unwanted noise through the sound system to cancel out the original noise.

But the electric power doesn’t last, and soon enough the little four-pot kicks in. The transition from off to on isn’t as smooth as it ought to be, though, and the car often has a little shudder when it refires. Oddly, it punches more wobbles through the car when it’s refiring on the run than when it refires via the start-stop system at traffic lights.

There are three modes for driving the A8 Hybrid, including pure electric, D for drive and S for sport, and all three fiddle with the gearbox, skid-control and steering as well as the throttle settings.

Beneath this layer of driver contact is another reality, because it can be driven five ways (though it decides some of them for itself without your involvement). It can run as either a pure electric or pure petrol-powered car, in hybrid mode, in energy recuperation mode or in boosting mode, when the electric motor is used to help the 2.0-litre engine’s performance.

The A8 Hybrid reacts to a press of its start button by seemingly doing absolutely nothing, though the air conditioner is immediately active, even if neither engine nor motor are… It will automatically (in eco mode) try to stay in pure electric drive as long as possible. Which, in our experience, isn’t very long. Then as soon as it runs flat (which is a relative term, because car companies only like to run their LI batteries in the middle 60 per cent of their range) or you need more gristle, it calls up the petrol powerplant.

There are times when it runs the petrol engine harder than you need for actual driving, just to make it turn the generator to charge up the battery, though you don’t notice this when you’re driving it. Instead, you notice that maybe the superb little four-cylinder engine has finally found a job that might be too much for even it to handle. Silken in lesser Audis, it has some notable harsh points in the A8, which probably relate more to its engine cradle and chassis stiffness as any inherent engine issues.

It’s brisk, without being fast. At 7.7 seconds to 100km/h, you can’t expect miracles on the autobahn, even if it does run to 235km/h. Besides, driving it like that defeats the purpose, doesn’t it?

It can use the electric motor as sort of an overboost to add its power to the standard power system (which it does to reach the 7.7-second mark), but that quickly drains its battery. It has a large battery gauge, and it’s particularly frustrating to see it refuse to charge to a full load, even though you’re pussy footing around it in eco mode.

The A8 Hybrid has one very cool function for “gliding,” where the petrol motor is switched off and disconnected from the driveline and the electric motor is charging the battery softly. Another good point is that its brake pedal is far more intuitive and progressive than the equivalent electric system in the S-Class.

The A8 Hybrid turns out to be smooth enough, without ever approaching the refinement of any other of the A8 range. It’s fast enough most of the time, but it presents few purchasing reasons that aren’t already covered in the standard line-up.

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