BMW has revealed official details of a range of M-badged diesel models set to go on sale later this year as part of the newly created ‘M Performance’ brand. The three models – named X5 M50d, X6 M50d and M550d – will be unveiled at the Geneva Motor Show in March, and all make use of the same tri-turbo 3.0-litre six-cylinder diesel. The M550d will be available as a saloon and Touring estate, and it produces 376bhp, delivered to the rear wheels. That’s still 176bhp short of the M5’s twin-turbo 4.4-litre V8, but 74bhp more than the most powerful diesel 5 Series currently on offer. While it\'s down on the M5’s power output, it’s not far off in terms of performance. BMW claims the M550d will accelerate from 0-62mph in 4.7 seconds, which is just three tenths of a second slower than the M5. The gains in fuel economy are genuinely impressive, though. Where the M5 only manages 28.5mpg and 232g/km of CO2, the diesel manages 44.8mpg and 165g/km. Those lowered emissions alone will save £625 on the price of road tax for the first year. Both X5 and X6 M50d models are four-wheel drive and boast similarly impressive figures all-round. Both are capable of almost 40mpg and 0-62mph times in the low 5-second area. Visually, the M Performance diesels aren’t as aggressive as their full-blown M stablemates, but subtle bodykits and alloy wheels mark the changes. The interior gets M-badgded door sills and a special steering wheel and seats. Chassis changes aren’t as comprehensive as they would be on M-badged models, but engineers have fitted the diesels with a few upgraded components and tweaked the suspension settings. Prices haven’t been released for the M550d yet, but the X5 and X6 M50d will cost £60,325 and £62,260 respectively.