The Audi A6 Avant is the estate version of the Audi A6 saloon, and is the basis of the more off-road oriented Allroad quattro. A revision in early 2015 involved some minor changes to the appearance, and more important ones to the equipment levels and fuel economy.

All Avants sold in the UK, and indeed all A6s in general (except the high-performance S6 or RS 6), have diesel engines. The six-cylinder 3.0-litre TDI is available with power outputs of 215bhp and 268bhp, while the similar but twin-turbocharged 3.0-litre BiTDI has 316bhp. The only four-cylinder unit in the range is the 187bhp 2.0-litre TDI ultra, which has a CO2 emissions output starting at just 109g/km. The ultra is front-wheel drive, the 268bhp 3.0 TDI and the BiTDI are four-wheel drive, and the 215bhp 3.0 TDI can be either according to the customer's choice.

The most common gearbox is now the seven-speed S tronic semi-automatic, though the BiTDI has a tiptronic CVT automatic with eight ratio holds. Ultra engine versions, meanwhile, are offered with a six-speed manual gearbox as a £1,490 cheaper alternative to the S tronic. There are three trim levels, one called SE and the others - S line premium and Black Edition premium – which cost about £2,500 and £4,600 more respectively. Rivals for the A6 Avant include the Mercedes E-Class estate.

Performance

The slowest A6 Avant is the ultra with manual transmission, but with a 0-62mph time of 8.7 seconds it can hardly be said to hang about. The 3.0 BiTDI can do the same run in just 5.2 seconds. Specifying four-wheel drive for the 215bhp 3.0 TDI saves you five tenths (despite also adding 70kg to the weight of the car), bringing the time down from 7.3 to 6.8 seconds.

For the best sound effects you'll want six cylinders, but the engine note of the ultra is very subdued and there's no clatter to damage the general sense of refinement.

With either gearbox, the ultra has a maximum towing limit of 1,800kg with a braked trailer. The equivalent figure is 2,000kg for the single-turbo 3.0-litre engines and 2,100kg for the BiTDI.

Ride and Handling

Wheel sizes start at 17 inches, and by the time you reach 19 inches the ride is simply too firm for comfort.

As is often the way with Audis, larger wheels improve the looks but wreak havoc on the ride quality. Wheel sizes start at 17 inches, and by the time you reach 19 inches the ride is simply too firm for comfort. 20-inch wheels are also available but best avoided, at least as far as the driving experience is concerned. Wheel size-related issues aside, A6 Avant models generally behave very well on the road. In particular, Audi has really hit the sweet spot with the ultra, whose steering is both light and very precise. Including standard and optional set-ups there's a choice of three different ride heights across a range of 30mm, lower ones meaning stiffer suspension. For reasons of weight saving, the rear springs are made of glassfibre reinforce plastic rather than the usual steel, unless you choose the optional air suspension.

Interior and Equipment

The oldest ancestor of this car was the 100 Avant launched in the early 1980s. Another 100 Avant from the previous decade was a hatchback, not an estate.

With the rear seats in place, the Avant has a luggage capacity of 565 litres, 35 greater than that of the A6 saloon. Fold down those seats (an easy, one-touch manoeuvre which provides an almost completely flat floor) and the capacity increases to 1,680 litres. In each case the Avant is slightly, though not much, roomier than the BMW 5-Series Touring and the Jaguar XK Sportbrake, though none of them come close to the 695 and 1,950 litres of the Mercedes E-Class Estate. Up front, the seats are very comfortable and there's enough space for almost anyone. The rear is early as good, though there's more room for heads than for legs. The changes for 2015 include updated versions of the optional MMI Navigation Plus and phone box systems. S line models, which previously had all-black upholstery and headlining, can now have them in a much cheerier colour called Lunar Silver. Audi owners will need no reminding that choosing optional extras can be an expensive business. Audi charges four-figure sums for MMI Navigation Plus and larger than standard wheels, which is not a good idea, as mentioned earlier. Other optional kit includes the £950 electrically adjustable front seats with a memory function on the driver's side, an "advanced" key with tailgate opening function for £750 and you’ll have to pay £335 for leather-covered door armrests.

Cost

Audi models tend to hold their value well, but bear in mind it might be hard to recoup the value of some exclusive (and expensive) optional extras come resale time.

For the lowest running costs you'll want the 2.0 TDI ultra with S tronic transmission and 17-inch wheels. In that form, the Avant has combined fuel economy of 67.3mpg and CO2 emissions of 109g/km, which leads to Vehicle Excise Duty payments of just £20 and a Benefit In Kind rating, for 2015-16, of 19%. Manual transmission means a best case of 65.7mpg and 113g/km, while on every version larger wheels generally mean an increase in running costs. A BiTDI on 20s has figures of 45.6mpg and 164g/km. Pricing is £2,000 higher than for the A6 saloon, and therefore starts at £33,955 for the ultra manual SE. The BiTDI Black Edition premium costs £52,750 before you start adding extras. Audi models tend to hold their value well, but bear in mind it might be hard to recoup the value of some exclusive (and expensive) optional extras come resale time.

Our Verdict

The Audi A6 Avant is an attractive, practical and sophisticated car with lots of space and some impressive diesel engines. The only real downsides are that it’s not quite as spacious as an E-Class and the larger wheels hamper the ride. Optional kit can also hike up the price substantially. But if the badge is important and you don't need all the space provided by the Mercedes E-Class, the Audi A6 Avant is as good a choice of large premium estate car as any. On paper the ultra is the least sexy model in the line-up, but for day-to-day use it's the one we'd go for, with small wheels.