The German brand's new 5 Series M Performance model sits alongside the M550i, with the M550d xDrive all-wheel-drive model packing a 3.0-litre six-cylinder diesel engine with quad turbocharging. BMW isn't new to adding plenty of turbos to its M diesel models, with the existing M50d versions of the X5 and X6 using triple-turbo power.
The new engine in the M550d, though, pushes the diesel engine into the frame as the most powerful six-cylinder diesel car, with BMW claiming 294kW of power at 4400rpm and 760Nm of torque from just 2000rpm, with 450Nm available from a low 1000rpm. It is 14kW/20Nm gruntier than the old M550d.
In the previous triple-turbo M50d there were two small turbochargers that worked to get things moving, and a third larger turbo that took over at pace. The new engine essentially sees the existing larger turbo replaced with a pair of small ones, and three turbos are permanently in use.
BMW claims the M550d can sprint from 0-100km/h in 4.4 seconds for the sedan or 4.6sec for the Touring wagon model, with the top speed limited to 250km/h. It is fitted with an eight-speed automatic gearbox and rear-biased all-wheel drive, and BMW claims fuel use of just 5.9 litres per 100 kilometres.
The M550d has lowered sports suspension with adaptive damper control available, as well as a variable ratio steering system. Styling wise, there is an M body kit with Cerium grey trim highlights that make it stand out from the regular models. There are 19-inch wheels standard (with 245/40 rubber up front and 275/35 at the back), and 20s are optional.
Inside there are illuminated door sill finishers, sports seats and leather/Alcantara/aluminium trim, while there are M-specific elements including the steering wheel with paddle-shifters.
BMW Australia has informed CarAdvice that the brand is only planning to manufacture the M550d in left-hand drive at this point in time, despite the fact the brand would "love to see it" sold here.