BMW M Performance Automobiles

BMW is trying to invent the Goldilocks of fast, prestige cars with an all-new model range of big, fast, sort-of-nearly M cars.

With some of its drivers finding the tyre- (and fuel-) burning rage of its M cars too hot, yet still needing more sizzle than the standard production diesels can muster, BMW is developing an all-new model range to squeeze in between the two.

BMW’s instant range of M Performance Automobiles (as they will somewhat clumsily be titled) won’t lack for performance, either, because they will be heaved to high speed by a new, in-line six-cylinder diesel engine with no less than three turbo-chargers.

The thumping new motor, developed exclusively for the M Performance Automobiles brand, boasts 280kW of power and 740Nm of torque from its 3.0-litres, and will this year find its way into its first four models: the M550d xDrive Sedan, the M550d xDrive Touring, the X5 M50d and the X6 M50d.

All four models will be shown at the Geneva Motor Show in March and will be on sale as early as May at prices that straddle the gaps between their body-shell equivalents in the BMW and M ranges.
With two small turbochargers and one large one, the M Performance Automobiles range promises both terrific light-throttle turbo response and top-end grunt. The tri-turbo motor was shown as a concept by Mercedes-Benz more than a year ago, but BMW has beaten its arch-rival in the race to production.

The 2993cc engine’s smallest, lightest turbo-charger starts whizzing just above idle and the second one chimes in at 1500rpm to instantly deliver the maximum torque figure (which it holds until 3000rpm). The biggest of the turbos is locked out until 2700rpm, crams in air until the engine’s delivering 280kW of power from 4000-4400rpm, then remains on station as the motor spins out to a petrol-esque 5400rpm.

It might not be as fast as the higher-revving petrol motors that dot the current 1-Series M Coupe, the M3, the M5, the M6 and the X5M and X6M, but the new motor ensures the M Performance Automobiles machines won’t lack for speed.

Even though the lightest of the M Performance Automobiles models, the M550d XDrive Sedan, will put just 5kg shy of 1.9 tonnes of mass onto a weighbridge, it will still explode to 100km/h in 4.7 seconds on its way to a speed limited maximum of 250km/h.

Its wagon sibling, the M550d xDrive Touring, is only two tenths of a second slower to 100km/h, while both 5-Series-based machines will sprint across a standing kilometre in 23.7 seconds.

While added speed is a key platform of the new brand, BMW had been trying for years to figure out how to reconcile M’s high-performance ethos with the increasing popularity and speed of big diesels. The proof is in the pudding, with the M550d boasting start-stop and an NOx storage facility in its catalytic converter to make it EU6 compliant, well before Europe’s new emissions standard becomes active.

All of this (plus start-stop and BMW’s EcoPro engine/gearbox software setup) helps the M550d xDrive Sedan to a combined fuel economy figure of 6.3 litres/100km with 165 grams of CO2 emissions/km as well. The Touring posts 6.4 litres/100km and 169 grams, primarily because it’s almost 100kg heavier, while their relative frugality (for M cars) convinced BMW that they only needed 70-litre fuel tanks.

Both the X5 M50d and the X6 M50d weigh 2150kg (dry), which dulls the engine’s abilities a bit, but still sees the X6 version take 0-100km/h honours by 0.1 seconds, with a 5.3-second sprint. Both cars run the standing kilometre in 24.9 seconds and both share an 85-litre fuel tank, but the X6 M50d is 0.2 litres thirstier for 100km, posting 7.7 litres to the X5 M50d’s 7.5 (which slips it beneath the barrier of 200grams/km for CO2 emissions). The biggest difference in the engineering layout of the SUV-based M Performance cars and the 5-Series models is that the SUVs don’t yet boast EU6 compliance.

BMW’s initial plan is to make the range entirely all-wheel drive, something the traditional M fan base has fought bitterly against for the petrol-powered cars. The electronically governed all-wheel drive system is an uprated version of BMW’s existing xDrive setup, and all four M Performance Automobiles models will run their axle-twisting urge through eight-speed automatic transmissions.

The all-wheel drive system is set up to make the cars feel and act as though they were rear-wheel drive, with the boffins setting it up to have just enough cleverness to intervene and sort out slides before the skid-control systems need to.

The Haus of M has also given the range its own tuning setup for the suspension, springs, dampers, body shell mounts, the engine and transmission mounts as well as tuning the electronic skid- and traction-control systems to match the increased grip and performance of the new range.

It kept the visual differences to a discreet level, though, with aerodynamic and cooling needs forcing changes to the front air intakes and some slight changes to the tail on all four models, along with unique wheels and mirrors and trapezoidal tailpipes. Both the 5-Series-based cars run on 20-inch wheels, while the SUVs have 19-inch rubber, though 20-inch wheels and tyres are optional. The other main change in the range is that the M550 xDrive Sedan uses steel springs all-round, while the other three use air suspension at the back, along with a self-leveling setup, because of their load-carrying status.

While the interior will be a luxuriant collection of leather and comfortable seating, BMW has added a surprise by collecting the tri-turbo motor’s natural engine note and sending it into the audio system so drivers can make the noise louder or quieter whenever they want to.

But if the added handling, grip, interior specification and refinement were predictable, the performance of the tri-turbo motor certainly wasn’t.

The intricate turbo-charging setup is small and uses pneumatically-operated flaps to divert the engine’s exhaust gases down alternative routes to the most-relevant turbo-charger whenever it needs to swap up to a bigger one or down to a smaller one.

For example, at 1490rpm, neither the second nor the third turbo-charger is even spinning, but a flap opens at 1500rpm because the smallest turbo has done its work and needs to hand on the relay batton.

All three turbo-chargers use variable-vane geometry to maximize their huffing and puffing, while the rest of the engine uses the latest in common-rail diesel technology to pump 2200 bar of pressure through its piezo fuel injectors.

The result is the most powerful diesel engine BMW has ever built, and it’s one that’s as fast on its feet and as clever as it is torquey. On its power stroke, the piezo injectors fire three pre-injection squirts into the combustion chamber, followed by one big power injection, then another four squirts post-injection.

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