IN THIS FEATURE Derby and diamonds Egg-shaped tactility Clever stowage

Unlike dear sibling's 2.5TDI, the new 2.7 sounds remarkably unlike a diesel from inside the cabin, with little grumble at idle; while under hard acceleration the Avant emits a pleasing, muted growl akin to a motor boat's. Nought to 62mph takes just 8.3sec and the claimed combined-cycle fuel consumption figure is 40.3mpg (though we returned only 32.4mpg in mixed driving according to the trip computer, though these are not always completely accurate). CO2 emissions are 187g/km and, like all A6 diesels, it's Euro IV-compliant even without a particulate trap, though one can be specified as an option.

But back to that clever load bay. It's 1.05m wide at its minimum, up to 1,941mm in length with the rear seats folded, and has a capacity of between 565 litres (seats up) and 1,660 litres (seats down). Impressive enough, but that's not the clever bit. The clever bit is that there are two rails down the sides of the load bay, which have sliding telescopic bars or recoiling straps attached, so that bulky loads can be securely fastened in a dazzling variety of ways. It's easier to see in pictures than to describe in text, so take a butcher's at the gallery. God bless the internet, eh? Then there's the fiendishly simple, and forehead-slappingly obvious, fold-out floor mat that can be pulled over the bumper to prevent scratches when loading bulky objects, or acts as a clean seat while you take your muddy boots off. Those, by the way, can then be stowed in a washable plastic compartment under the boot floor.

Boot volume up to 1,660-litres

That the tailgate both opens and closes electrically is the final piece of the Avant's practicality arsenal, and adds the touch of class that luxury motor or, er, a Honda Accord estate, can offer. But the A6 Avant's biggest assets are not its luxury pretensions but its versatile load bay and exceptional engines. That it's a viable way to spend £50,000 on something other than a hoofing-gurt-SUV is a boon for some, but the Avant's best forms are the cheaper ones, for those who more commonly transport nippers and Racing Posts than diamonds and caviar.