Road Test: Audi A7 3.0 TDI 5dr Multitronic

For modern car makers, capturing a genuine new niche in the market is like drilling into an untapped oil reserve. No, it's better than that. It's like drilling into an untapped reserve located just six inches below the surface and next door to a lap-dancing bar with non-stop happy hour. And a pool table.

Audi wants some of that oil. It has been drilling feverishly in the last decade, more than doubling its model line-up in a bid to hit black gold, churning out crossover after niche-buster, each promising to answer a desperate need unexploited by other, less prescient, manufacturers.

But, unusually, Audi doesn't claim to have struck virgin oil with its latest genre-blurring offering, the A7 Sportback. Instead, the prospectors in Ingolstadt have set up their heavy drilling equipment right next to - hell, on top of - the Mercedes CLS. The War and Peace-scale document accompanying the A7 is jammed full of comparisons with the car that tapped into the undiscovered Big Coupe Well, declaring the Audi to be cleaner, faster, more economical and entirely statistically superior to the CLS. That the A7 comes out better isn't surprising - manufacturers don't tend to highlight comparisons where their own car looks off the pace - but Audi's message is clear. Forget ‘offering a unique proposition' or any of that nonsense: this car is out for the CLS.

All of which is lightly bemusing, because the A7 isn't exactly a rival for the CLS. Where the Merc is a coupe-style saloon, a genuine four-door, the Audi is a coupe-style hatch, a five-door. What the A5 Sportback is to the A4, so the A7 Sportback is to the A6: a four-seater with a proper - and properly accessible - boot.

Only... it isn't exactly that, either. An A6, we mean. Longer and lower than the currently A6 saloon, it sits on an all-new platform (which will, admittedly, underpin the next-gen A6) and is built from steel and aluminium: the A6 is all-steel. The two cars don't share a body panel. The A7 looks fantastically low and sleek. The A6 doesn't.

At least the A7 is a four-seater, though, right? Er, not quite. Well, it is, in the sense that it only has four seatbelts. But where the CLS treats its rear-seat occupants to a pair of sculpted chairs, the A7 has a conventional rear bench... with the middle belt removed. There's a cushion there and everything. Audi says it'll offer a five-seat A7 if there's sufficient demand. The conversion shouldn't take long. Headroom for back-seat passengers is fine if you're under six foot, but monied owners who want to ride in the back of their Audi will still buy an A8.

A7 drivers will be firmly wedged in the driver's seat, and a thoroughly ritzy place it is too. Audi makes some of the best cabins in the business, and this is one of the best of the best, easily approaching A8 levels of luxury. The optional layered wood trim is reminiscent of something from the budget end of the Ikea catalogue, but beyond that the A7's cabin is beyond reproach and, should you flash the credit card enough, dripping with enough tech to satisfy the hardiest Tomorrow's World presenter.

See more pics of the Audi A7 Sportback

It's the first Audi to get a full head-up display, which, should you choose, displays the speed limit of the road you're on. This initially seems a sensible idea but will eventually cause you to start screaming at it furiously, or else just switch it off, whichever comes first. The A7 gets the option of night-vision cameras, a self-parking system, and also borrows the A8's touchpad to control the various multimedia options, including a Google Earth-enabled satnav. We thoroughly recommend this optionif someone else is paying the 3G data bill. But beware flagrant box-ticking: flicking through the options, we specced an A7 up to over £90k.

Keen-eyed readers will note that we've comfortably reached the ninth paragraph without remarking on how the A7 drives. Not because it's a dog - it isn't - but because it is, in fact, unremarkable. For the most part, this unremarkability isn't a problem: the A7 - particularly in four-wheel-drive guise - is an easy car in which to make rapid and unruffled progress. Though the torque distribution is slightly rear-biased, it's impossible to provoke the A7 into any sort of tail-wagging antics: you'll only find a near-inexhaustible supply of grip, no more than the merest hint of body roll through even thequickest corners and, at the verylimit, gentle understeer.

Steer clear of the 20-inch ‘S-Line' alloys and refrain from clicking the adaptive dampers into knobbliest mode, and the A7 doesn't ride too badly, either. We'd guess it won't tackle smashed-up UK tarmac with the fluency of the Jag XF, but it's less brittle than most sporting Audis.

The 245bhp, 3.0-litre diesel is the best of the all-V6 engine line-up - there's a lower-powered version of the same engine (only available with a CVT gearbox; avoid) and a pair of petrols: a 204bhp, 2.8-litre unit and a supercharged 3.0-litre. The latter essentially a detuned version of the S4's engine and, though mighty quick, isn't rousing enough to justify the premium over the quicker diesel.

Which tells you all you really need to know about the A7 on the road. It's fast and grippy, but it isn't a whole lot of fun to drive. After pummelling the A7 through a series of tight bends, you stop and think, ‘My goodness, that was indeed some unusually rapid progress.' Not, ‘Hell, let's do that again.' It doesn't give much back to the driver: the steering, though sharp enough, feels artificial, the chassis erring on the side of inert caution.

Does this matter? Not much, probably. How many A7s willbe mercilessly thrashed into tyre-shredding submission? Not many (and besides, there's an S7 on the way for that). For its prime function- ensconcing a family of four in tech-laden, continent-crossing comfort - the A7 is brilliantly fit to task. At least until the new CLS turns up next year, it has the beating of the big Merc in just about every department.

And - whisper it in case it creates civil war within the VW Empire -it might cause the Porsche Panamera a few problems too. Audi doesn't mention the four-door, five-seater luxo-coupe anywhere in the press bumf on its own, er, four-seater five-door luxo coupe. Obviously any A7 would get a bloody nose in a fight with the £100,000 Panamera Turbo, but consider: the base-spec Panamera is powered by a V6 engine putting out around 300bhp and costs around £60,000.

The top-of-the-range petrol A7 is powered by a V6 engine putting out around 300bhp and costs around £55,000. The Audi is quicker, more economical, gets more kit, has 4WD and is far better looking. If you're going to thrash your big coupe to the limit on every commute, you'll want the Panamera, but the rest of the time? We wonder. Strong-arm drilling tactics successful, Audi.