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New BMW X3 M and X4 M launch with 510hp

Re-engineered turbocharged 3.0-litre six-pot is already more potent than the S55 unit in M4 GTS

By Sam Sheehan / Wednesday, February 13, 2019

Talk about intent. BMW's M division has sent its first proper X3 and X4 SUVs out of the gate with a re-developed inline six producing more power than the top version of its previous go-to engine. The UK is only getting the 510hp X3 M and X4 M Competition range-toppers (there's no plan to introduce the entry-level 480hp version here) so the right-hand-drive variants will be 10hp better off than the outgoing M4 GTS from the get-go. And - more impressive still - 70hp and 24hp ahead of the Porsche Macan Turbo Performance Package and Mercedes-AMG GLC 63, respectively. Conveniently, it matches Alfa Romeo's Stelvio Quadrifoglio.

The power hike comes courtesy of significant upgrades to BMW's S55 turbocharged 3.0-litre motor to create a new one, the S58. Its maker says a new, 3D-printed head allows for better temperature control thanks to its more efficient design, while lightened internals have lowered the rotating mass. Then there's a new iron coating for the cylinder walls, new injectors for increasing pressure from 200 bar to 350 bar, new monoscroll turbochargers and... well, you get the point.

Combined, the improvements have enabled engineers to extract 443lb ft of torque from 2,600rpm to 5,950rpm and 510hp at 6,250rpm from the revamped six-cylinder. The engine's elasticity has also been extended so it "sustains power delivery" all the way to the 7,300rpm redline.

Flat out, BMW's new straight six can accelerate its M division SUVs from zero to 62mph in 4.2 seconds and onto a 174mph top speed, assuming the buyer's ticked the Driver's Pack to remove the standard-fit 155mph limiter. Not enough to threaten the fastest version of its previous M4 - but sufficient to keep up with the V8-powered AMG GLC 63, and leave the Porsche Macan Turbo Performance Pack in each model's wake. Alfa's fastest Stelvio remains top dog, however.

To ensure that neither offering is just a straight-line bruiser, both have been fitted with an evolution of the M5's all-wheel drive system, which is said to provide the SUVs with genuine on-throttle adjustability. The setup, powered via BMW's new eight-speed Steptronic torque converter, distributes torque using a multi-plate clutch, is said to be rear-biased, but doesn't go so far as to offer a two-wheel drive mode like the one provided in the M5. These are SUVs, after all.

To better help the architecture handle the strain of all this, BMW has equipped the X3/X4 M with added braces at the front and rear, and from August 2019, a carbon fibre-reinforced plastic strut brace will be offered as a lighter, still more rigid option. The bulkhead has also been given an A-strut like the one seen in other M models, while struts between the suspension and front section really hunch things up at the business end.

Underneath, the cars get electronically-controlled adaptive dampers as standard and there are enormous cast iron brake discs of 395mm and 370mm diameters to slow things down. They're located behind standard-fit 21-inch alloy wheels as per the Competition package, wrapped in Michelin Pilot Sport 4S rubber. For the car's steering system, BMW's variable ratio electromechanical system is the only option.

To emphasise their added potential, the Competition models also get aesthetic extras such as sculpted door mirrors, beefed-up bumpers and widened arches, while the cabin comes with sports seats wrapped in Merino leather and BMW's latest infotainment technology. Neither is going to be short of presence or kit, then.

If you want one, BMW's taking orders today, with prices starting from £77,070 in Britain and first deliveries are scheduled to arrive this September. Of course, if SUVs are not your thing, then it's worth remembering that the new M3/M4 will make use of the same basic powertrain hardware when they arrive next year. Think of these as a high-sided preview of what's still to come...

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