BMW’s most expensive SUV, the X8 is likely to be unveiled in 2020. It will be pitched as a coupé-styled rival to the upcoming Range Rover coupé and Audi Q8. It could also compete in fully loaded guise against low-end versions of the Bentley Bentayga, Lamborghini Urus and Rolls-Royce Cullinan. The BMW 'X8' moniker has been trademarked in markets around the world, with markets in the Far East being the latest to have X8 trademarks filed.

Discussions are believed to centre on the platform structure that the X8 would need and whether it should be a coupé version of the X7 (which was revealed at the Frankfurt motor show and goes on sale in mid-2018) or a long-wheelbase version of that car, which would free-up additional rear space and allow for a sweeping roofline.

Either way, the X8 is likely to have the option of four or five seats across two rows, rather than the seven seats in three rows seen on the X7. As such, the X8's emphasis will be on delivering luxurious rear-seat travel, with the materials and finish chosen to further that goal rather than being focused on outright practicality.

While the latter idea seems to be favoured by many, it adds a potential complexity to the project. The car may need to be built on a hybrid platform that merges BMW’s CLAR modular platform (which underpins the firm’s other X models) with the Rolls-Royce Cullinan’s new aluminium structure. This would achieve rigidity without adding too much weight or cost.

The decision on how sweeping a roofline the car would have is said to hinge on two factors – whether the need for the rear seats to be commodious (given that the X8 is likely to be chauffeur-driven for many owners) and how much differentiation is required to give the car a character that sets it apart from the X7. It would be problematic to achieve the coherent styling of the sweeping roofline without bringing down the roof-height ahead of the boot line.

The X7’s dimensions in comparison to rivals suggest there is room for a longer version in BMW's line-up. It is 5,020mm long with a wheelbase of 3,010mm. The Mercedes-Benz GLS, on the other hand, is 5,131mm long and has a wheelbase of 3,076mm. Meanwhile, a Range Rover is 4,999mm long and has a wheelbase of 2,922mm in standard form.

Power for the mysterious X8 is likely to come from the same powertrain as the X7. Although, considering the car's sales are focused in China, Russia and the Middle-East, initial offerings may be confined to higher-powered petrol or plug-in petrol-electric hybrid drivelines. Given the target market, it is highly possible that we would see a V12-engined X8, powered by the 600hp, 6.6-litre unit seen in the 7 series.

The petrol-electric hybrid powertrain is believed to be derived from the same set-up used by the 740e xDrive iPerformance –  a turbocharged 2-litre, four-cylinder engine operating in combination with an electric motor in the forward section of the gearbox housing – albeit with a larger-capacity battery to give a 100km electric range.