What is it?
BMW was initially quite reticent to apply its revered M badge to any of its dedicated four-wheel drive models over concerns that such a move may harm the blue chip image enjoyed by its performance models.
But after witnessing a huge increase in demand for performance based four-wheel drives, it launched the rapid X5 M50i and X6 M50i in 2009 prior to launching even more powerful successor models in 2014.
Now, some six years after its first performance SUVs first hit showrooms, BMW has introduced a smaller and more affordable alternative in the form of the X4 M40i; a car clearly aimed at challenging the likes of the recently introduced Porsche Macan GTS.
The X4 M40i takes the turbocharged 3.0-litre in-line six-cylinder engine of the X4 xdrive35i and combines it with various performance enhancing components already used in the M3 saloon and M4 coupe and cabriolet.
Included in the M division makeover of BMW’s latest straight six are new pistons featuring a new top ring design, additional boost pressure for the twin-scroll turbocharger, revised crankshaft bearings, a modified inlet manifold for improved breathing potential and a separate oil cooler. They’re similar changes to those brought to the engine used by the new M2, no less.
As a result, power has risen by 54bhp over the existing top-of-the-line X4, taking it up a Porsche Macan GTS equalling 355bhp.
It is a sufficient lift to provide the 1840kg X4 M40i with a power-to-weight ratio of 193bhp per tonne - some 27bhp per tonne better than that of the 1815kg X4 xDrive35i and a 6bhp per tonne increase on the Macan GTS.
There’s greater torque, too. Some 48lb ft of it to be precise, endowing the latest high-riding M model with 343lb ft of twist on an impressively wide band of revs between 1350 and 5250rpm.
In combination with a standard eight-speed M-Steptronic automatic gearbox with a unique M division software map and a four-wheel drive system that runs a more rearward bias than that seen in standard X4 models, the powered-up engine provides the X4 M40i with a claimed 0-62mph time of just 4.9sec along with a limited 155mph top speed.
By comparison, the X4 xDrive35i receives respective figures of 5.5sec and 154mph, while the Macan GTS boasts an official 5.2sec and 159mph. Fast by class standards, then.
Accompanying the wholesale lift in reserves is reworked suspension featuring increased camber and strengthened wishbones up front, as well as stiffer springs, altered electronic mapping for the adaptive dampers and larger diameter anti-roll bars at each end. The variable ratio electro-mechanical steering system also receives specific tuning for what the BMW M division describes as “heightened steering precision”.
The standard wheel and tyre package mates 245/45 R19 front and 275/40 R19 rear Michelin Primacy run flats with 8.5J x 19-inch and 9.5J x 19-inch rims. Those seeking ultimate grip should go for the optional package, which uses 245/40 R20 front and 275/35 R20 Michelin Pilot Super Sports with 8.5J x 20-inch and 9.5J x 20-inch double spoke alloys.