SPY PICS: BMW X7 mule snapped

For all the high-tech assaults the premium German car makers have made, the Range Rover still holds a unique place at the top of the luxury SUV tree.

But the British icon might not be sitting there alone for too much longer. First, there is about to be a Bentley SUV, followed by a Lamborghini and even a Rolls-Royce.

And then there will be this. Snapped hiding behind BMW's prototyping workshop in Garching, near Munich, is one of the early prototypes for the 2018 X7.

BMW's largest ever production vehicle, the X7 will arrive with three rows of seats and enormous luggage space, with a far greater focus on the middle-row legroom than in the current X5.

Codenamed G07, the X7 will focus on outright luxury in a way that its more mainstream nature denies with the X5, sources admitted, and even more than the 7-Series itself.

It will be based on an all-new large car architecture, which BMW just unveiled beneath its new 7-Series limousine, making the five metre-plus SUV lighter than the current X5.

The prototype snapped here is believed by sources to be proving the longer powertrain and suspension concepts.

The production architecture will also find its way into Rolls-Royce's production version of the Cullinan concept SUV and the next X5 and X6, both of which will begin to cycle out shortly after the X7 arrives.

Sources at BMW have admitted the X7 will be at least half a metre longer than the X5 and a touch wider, too. Unlike the tiny X5 third-row seats, which are suitable for small children and, even then in short bursts, the X7 third-row seats have been designed to accommodate adults where needed, but still fold down into the cargo floor.

With its weight pulled down by a multi-material mix of hot-formed steels, aluminium and structural carbon-fibre pieces trickled up from the i3/i8 program, its weight is expected to be pegged below 1900kg for the entry-level versions.

The range will begin with 3.0-litre, six-cylinder petrol and diesel engine variants, plus a next-generation V8 engine. There will also be a plug-in hybrid variant with, finally, more than 50km of electric range thanks to BMW packaging the bigger batteries right from the car's conception.

Critically, in the battle with Range Rover, it will be the first SUV from BMW to boast a V12 powerplant, and will take on the 7-Series' 6.0-litre engine. All of its powerplants will mate up with eight-speed automatic transmissions.

 It is expected to ride on air suspension across the board, with the weight of the system offset by aluminium suspension parts.

BMW insiders believe the addition of the air suspension will give the big SUV a surprising amount of off-road ability, especially when it's combined with a new-generation software package.

While it will focus far more on luxury than off-road ability, BMW believes its all-wheel drive X7s need to match the Range Rover for its own credibility, even a pure rear-wheel drive version is also planned.

BMW expects volumes of around 50,000 X7s a year, though there will be no M version to give it some additional profit cream at the top of the market.

It will be built in Spartanburg, South Carolina, alongside the X5 and X6, and BMW is expected to focus on selling the X7 in the United States, China, Russia and the Middle East.