The diesel M-car onslaught continues with news of BMW's new M50d X5 and X6 models. While the M-badged 5 Series saloon may be grabbing most of the attention it is the SUVs that will hit the market first, arriving in June costing £60,325 for the X5 M50d and £62,260 for the X6 M50d.

Like the M550d both cars are powered by a new tri-turbo 3.0-litre six-cylinder diesel engine that was produced specifically for BMW's new M-Performance sub-brand. Outputting 381hp and 740Nm of torque the new engine allows the xDrive four-wheel drive enabled X6 M50d to hit 62mph in 5.3 seconds (5.4 seconds for the X5 variant) from standstill before sailing on to a top speed of 155mph.

A new eight-speed Sport automatic transmission had to be developed especially for the range but despite the performance on offer the X5 M50d can still return 37.7mpg with the X6 M50d only fairing slightly worse, returning 36.7mpg. The impressive economy is thanks to optimised EfficientDynamics technology that includes stop-start and ECO PRO mode.

Both cars are fitted with air suspension on the rear axle as standard with self-levelling adaptive drive standard on the X6 M50d and available as an option for the X5 M50d. BMW's M-Division has tuned the suspension, springs and dampers, body shell, engine and transmission mountings of all cars to allow them to drive like an M-car and thanks to subtle styling changes they will look the part as well.

The body kits fitted to the X5 and X6 M50d are slightly different from those fitted to conventional M cars but trapezoidal exhaust tailpipes, 20-inch M-badged alloy wheels and M Performance specific paintwork will leave you in no doubt that you are in a special car. The interior of each has also been given the M treatment, with unique stainless steel sill plates, leather-bound dashboards and M-specific steering wheels and seats.