to the X4 what the M135i is to the 1 Series; a little faster and a little more dynamic than standard while still being fairly closely related. Active differentials and dual-clutch 'boxes are kept back for the full-fat M cars.
For the M40i, its basis is the 35i that isn't available in the UK. In fact, there aren't any petrol X4s offered in the UK. From that 35i, the M40i adds another 60hp and 48lb ft, taking the totals to 360hp and 343lb ft. Pretty big numbers, even in a car that weighs 1,915kg. With the standard eight-speed auto, BMW claims 0-62mph in 4.9 seconds and 155mph. Stateside Golf R owners beware...
The engine is a reworked version of the M135i 3.0-litre in fact, rather than the new modular straight-six as found in the 340i. Just to help the BMW naming confusion a little more... It remains a great engine though, super smooth and revving out eagerly. The noise is classic BMW too, even if the vehicle isn't. It actually sounds less augmented than in the 1 Series, and given how rapid the X4 is to 55mph (honest, officer) there is no reason to doubt that 0-62mph time.
Mooching along a nondescript American road, the M40i is entirely pleasant. The driving position achieves that neat trick of ensconcing the driver while also keeping you sat relatively high. The interior is sumptuous, the gearbox shifts seamlessly and the ride - albeit on well surfaced roads - is just fine.
Shall I compare thee...
Well it's no M2, that's for sure. Of course that's not the most relevant comparison but given it was driven on the same road just about an hour later, that's inevitably where your train of thought picks up. However, given the constraints of its size and mass, it's not half bad. The test cars were fitted with the optional 20-inch wheels and Michelin Pilot Super Sport (yes, same as on the M2) tyres, so grip is just colossal. Pitch it into turns at what appear unfeasible speeds and it gamely clings on, only succumbing to understeer very late on. It's hardly a delicate or fulfilling process but it's a fairly astonishing feat nonetheless. It would be a lie to suggest the rear bias of the xDrive was felt that much but for covering ground really rapidly - with the added advantage of that lofty driving position - the X4 M40i is quite the device.
the Cachagua Road do reveal a few weaknesses though. Having experienced the improvements made with the M2's steering, the X4 is a reminder of the bad old BMW systems, very artificially weighted and with odd resistance off centre. And there are those moments when all the M Performance modifications in the world can't save the M40i from the laws of physics; just sometimes it hits a bump and the damping can't quite keep up with all that's being asked of it, an unpleasant lurch the consequence.
For the most part it's very good at the Sports bit of Sports Activity Coupe, then in Eco Pro will coast its way home again with the minimum of fuss. It's quite a box of tricks, the X4 M40i, albeit not a particularly appealing box...
Yes, the appearance had to feature at some point. It's amazing we've made it this far really. Even on these rims it looks underwheeled, while the body brings together so many angles and surfaces that it's quite a confused overall shape. But then an X4 would never have happened if the X6 hadn't been a success, so judgement on how the X4 looks is probably redundant.
Absurd though it may sound, it does seem surprising that BMW isn't bringing the X4 M40i to Britain. It certainly isn't one for the M purists, but it's a broadly talented car and there are already rivals on sale: see the Porsche Macan GTS and the Jaguar F-Pace V6 S, plus the Audi SQ5 for those willing to consider diesel. They may not be core PH cars, but their current popularity cannot be denied. Or BMW will simply skip the M Performance addition to the X4 range and hit us straight with that X4 M. Be prepared...
BMW X4 M40i
Engine: 2,979cc turbocharged inline-6
Transmission: 8-speed automatic, all-wheel drive
Power (hp): 360@5,800-6,000rpm
Torque (lb ft): 343@1,350-5,250rpm
Top speed: 155mph
Weight: 1,915kg (unladen EU)
MPG: 27.4 (NEDC combined)
Price: Not for UK sale, $57,800 (£40,100) in US