Review of the new Audi A6 TDI Multitronic Range

There's something to be said for German efficiency. Audi have long been a paragon of the buttoned-down pursuit of technical perfection and few models in their line up better exemplify this than the A6 diesels when allied to the multitronic gearbox. Most will figure that this gearbox is simply an automatic which allows the driver to sequentially snick up and down the gears but it's a good deal cleverer and far more efficient than that.

The trouble with buying decently sized diesel cars is that their qualities are often blunted by old fashioned and, to put it bluntly, dumb automatic gearboxes. The advantages of fuel efficiency and low emissions are often dulled when trying to drive a torque converter and you often miss out on that instant urge that the best turbodiesel engines serve up when it comes to overtaking. Planting the throttle and waiting one-pause-two while the software figures out that it should be kicking down can often lead to heart in mouth moments. There has to be a better way.

Audi certainly think so and they're in the fortunate position of holding most of the cards. While Mercedes may have the cleverest automatic gearbox in their 7G-TRONIC system, Audi have by far the best sequential manual system with their much-envied DSG and they also have something that sits between these two extremes, the Multitronic CVT. This CVT approach allows enthusiastic drivers to get some enjoyment from the gearbox when they're in the mood but at other times it can be left to its own devices to replicate an automatic. There's very little loss in performance over the manual and likewise little to choose between them at the pumps.

In fact when compared with a manual box, most drivers will see an improvement in acceleration and fuel economy with the Multitronic system. The electronics incorporate a Dynamic Control Programme (DRP) which monitors both the driver and the driving conditions. It assesses the way the driver uses the accelerator pedal and determines whether the emphasis is being placed on performance or economy. If a more leisurely driving style has been adopted, the system translates the engine speed into propulsion via a low ratio (overdrive) at road speeds as low as 37mph on the basis of a stored characteristic map which places the emphasis on economy.

"The TDI diesel and the Multitronic box complement each other smartly"

If the driver opens the throttle completely and kicks down, the system immediately switches to the stored characteristic map for sports driving and alters the ratio to 'underdrive'. As a result, the high engine speeds required for maximum output become available even at low road speeds. In normal driving conditions, the system selects the most favourable ratio between these two extremes and, unlike conventional automatic transmissions, it does so imperceptibly and entirely without jolting. The electronics also take into account uphill and downhill gradients and assist the driver by compensating for the added load or boosting engine torque Accordingly.

Arguably the most ingenious feature of these electronics is the aforementioned 'manual' mode which can be selected by moving the gear lever to the right of the gate. It offers seven fixed transmission stages, each selected with a touch of the gear lever or optional steering wheel-mounted rocker switches (which we'd recommend). Again, on the move, the gearchanges are jolt-free. As with ordinary 'Tiptronic'-style gearboxes that offer this kind of 'manual' set-up, it's something that's fun to use for a time but a feature that all but the most enthusiastic will quickly tire of.

The Multitronic box is offered on two diesel models, the entry-level 2.0TDI and the punchier 2.7TDI. The 2.0-litre model starts from £26,970, incorporating the £1,450 premium that Audi charge for this gearbox - and offers superb fuel economy. Its 40.3 mpg average economy figure is far in excess of the 24-28mpg you can expect from Audi's V6 and V8 petrol units. It sounds good but reading this, you're probably gearing yourself up for some disappointing news regarding the car's performance. Sure enough, it isn't the executive express that every young go-getter dreams about as they struggle up the corporate ladder but, as we've explained, V8 power comes with some fairly prohibitive bills. The 2.0-litre TDI makes a decent account of itself with 0-60mph acceleration of 9.9s and a 127mph top speed. The engine doesn't feel unduly troubled by the A6's substantial mass with a nice slug of torque low down in the rev Range translating into impressive flexibility. The engine and gearbox are well soundproofed, insulating the driver from the occasionally discordant sounds of the CVT.

The 2.7-litre with Multitronic starts at £28,965 in SE trim and this represents a very modest premium for the additional performance on tap. Whereas the 140bhp 2.0-litre model can feel a little breathless under hard acceleration, the 2.7-litre engine just pulls like a locomotive. Essentially a downsized version of the 3.0-litre TDI unit, the 2.7-litre powerplant is the lightest in its class while still turning out a punchy 180bhp. It needs all that power and all of its 380Nm of torque as well, as the A6 is a seriously sizeable slice of metalwork. Unlike early TDI engines, which possessed a savagely spiky power delivery, this one does its best work in a comparatively broad Range between 1,400 and 4,250rpm, and will get the A6 to 60mph in just 8 seconds. A top speed of 140mph is a very creditable achievement for a diesel car although the fuel economy and emissions figures are predictably good. On the combined cycle - a simulation of town and open road driving - the A6 2.7 TDI will return an average of 37.7mpg. Business users will be keen to see that carbon dioxide emissions are a very reasonable 200g/km.

Available in both saloon and Avant estate guises, Multitronic is an option that even those previously disposed against CVT gearboxes really need to investigate. In offering the convenience of an automatic with the efficiency of a manual 'box, Audi have established a very German solution to this problem.

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