Audi A8 Hybrid

What is it?

This is new Audi A8 hybrid, which combines the familiar 208bhp 2-litre turbocharged petrol engine with an 53bhp electric motor backed up by 1.3kWh battery pack.

It’s an unusual mix for a range-topping saloon, joining a relatively hum-drum four-cylinder engine with a hybrid electric transmission. In this rarified segment, the hybrid cars are usually V6 (the Mercedes S400, not currently sold in the UK) or V8 (BMW 7-series, also not sold here).

Only the V8-engined Lexus LS 600h hybrid is in the same sector, but its engine is twice the size and its economy - 30.4mpg and 218g/km - is well behind this A8’s 44.8mpg and 147g/km.

The battery – which sits in the boot – is tiny by EV standards and offers just 3km of battery-only range, although the A8 can manage a top speed of 62mph on the battery. The electric motor is squeezed into the bell housing of the transmission casing, where the torque convertor would otherwise sit. It rotates around the clutch pack that connects the 8-speed gearbox to the dual-mass flywheel.

On the outside, this car is also distinguished by its own 19in wheels, unique silver metallic colour. Inside, its gets a different instrument pack, with the rev counter replaced by a ‘power meter’ that shows the energy flows between the engine, motor and battery pack.

Audi has also fitted an active noise cancellation, which uses four microphones in the headlining, and sends out ‘anti-phase’ sound through the sound system. The company claims noise levels can be reduced by as much as 75 per cent.

What’s it like?

Pretty good. Although this is a humble four-cylinder engine, you hear it more than feel it. Under acceleration, the engine’s note is dull and droning, but any harshness is damped away before it reaches the driver’s contact points.

Otherwise, this car is smooth and swift enough. With the electric motor assisting the engine under acceleration, there’s plenty of smoothly delivered torque, so the car does a pretty reasonable impression of having more than four cylinders.

When the car is coasting, the engine will stop and de-couple from the transmission. But when the driver re-applies the gas, you can just about sense a slightly clunk in the transmission as the engine re-starts and re-engages. Otherwise, the transmission is pretty seamless.

On German roads it rides pretty well, although the 19in wheels will drop heavily into potholes. It encourages the driver to relax and steer along at a moderate pace, which is probably appropriate for a car of this size and type. It’s hard to pinpoint when the noise-cancellation is working, but the cabin is certainly very quiet.

The rest of the car is pretty standard A8, aside from the different instrument pack and includes adaptive air suspension, double glazing, Valcona leather is standard, 3-zone climate control, Sat-Nav with a hard drive and a 630w Bose Hi-fi.

Should I buy one?

In Europe the A8 Hybrid costs 77,000 Euros in standard spec and it arrives in the UK in the first quarter of 2013. The standard-issue 3.0 V6 front-drive diesel A8 returns 158g/km, so the hybrid promises better economy. It is also marginally more economical than the 3.0-litre V6 diesel quattro, which is similarly priced.

However, the serious downside is that boot space is greatly compromised by the battery pack, a serious downside for a car of this size and for something that is often used for shuttling VIPs.

The big markets for this car, says Audi, is in China and the US. In the UK, it is little more than an eco-curio unless you don’t need the boot space, want the best possible economy available in an A8 and really dislike diesel.

Audi A8 Hybrid

Price: TBA; 0-62mph: 7.7sec; Top speed: 146mph; Economy: 44.8mpg; CO2: 147g/km; Kerbweight: 1870kg; Engine type, cc: 4cyls, 1984cc, petrol, turbo, electric motor; Installation: Transverse; Power: 208bhp at 4300-6000rpm, 53bhp electric motor; Torque: 258lb ft at 1500-4200rpm, electric motor 155lb ft; Gearbox: 8-spd tiptronic auto