BMW will introduce a new range of performance-orientated M division-developed diesel models later this year. The new oil-burners will get an initial public airing at the Geneva motor show in March and are set to reach the UK later this year.
The four-wheel-drive X5 M50d and X6 M50d will arrive first, in June. Rear-wheel-drive M550d saloon and M550d Touring models engineered specifically for right-hand drive markets are tipped to go on sale in October. The rear-drive pair will come to the UK in place of the four-wheel-drive M550d xDrive saloon and Touring variants that will be offered elsewhere in left-hand drive only.
See official pics of the M Performance diesels
The four cars represent an M division first, with all running a newly developed version of BMWs 3.0-litre, six-cylinder diesel engine.
The new powerplant is fitted with a triple-turbo induction system that BMW sources suggest is set to revolutionise the efficiency and performance credentials of traditional combustion engines, in both diesel and petrol formats.
The new models will form the basis of what BMW has dubbed its M Performance range. They have been conceived to slot into their respective line-ups between the top-performing standard model and full-blown M model in terms of outright performance, dynamic ability, equipment levels and price. In the case of the M550d saloon, this is between the 550i and M5.
The new M-developed diesel engine comprehensively outguns BMWs widely used twin-turbo 3.0-litre in-line six. It develops 376bhp between 4000 and 4400rpm and a sturdy 545lb ft of torque from 2000 to 3000rpm.
These figures are 74bhp and 103lb ft higher than those of the most powerful version of BMWs existing twin-turbo 3.0-litre six, as fitted to the 740d, giving it a spectacular by diesel standards 126bhp and 182lb ft per litre.
Although 176bhp shy of the M5s twin-turbo 4.4-litre petrol V8, the M550d saloon boasts 44lb ft more.
In each of the M Performance models, the new engine is mated to a beefed-up version of the existing eight-speed automatic gearbox and, for left-hand drive markets, a specially tuned version of BMWs four-wheel drive system. Together, this set-up gives the M550d xDrive saloon 0-62mph acceleration of 4.7sec just 0.3sec slower than the new M5.
Because of the M550d xDrive saloon and Tourings lack of right-hand drive compatibility, UK versions will be rear-wheel drive only resulting in what BMW insiders say is a 70kg reduction in kerb weight.
BMWs EfficientDynamics fuel-saving features including stop-start, brake energy recuperation and on-demand function for engine ancilliaries help the saloon to return 44.8mpg on the combined cycle, giving the M550d xDrive a CO2 rating of 165g/km, the same as the 535d.
M division has also provided the M550d xDrive saloon, 550d xDrive Touring, X5 M50d and X6 M50d with unique steering ratios, chassis settings and, in some instances, chassis components conmensurate with their M-car siblings.
Each M Performance car will get subtle styling changes to differentiate them from their standard and M-car counterparts. The interior of each car has also been given the M treatment, with unique stainless steel sill plates, leather-bound dashboards and M-specific steering wheels and seats.
The X5 M50d will cost £60,325 when it goes on sale in June and the X6 M50d will be £62,260. Prices for the M550d saloon and Touring have not yet been revealed.
. the specs are good and can't wait to see some road test of it. 
