There's no doubting that the BMW X4 benefits from a little work by M GmbH, making the opinion-dividing SUV more engaging and less benign than ever, yet it's all but an irrelevance here in Ireland, where there's precious little demand for a petrol-powered high-performance car such as this. Shame the X4 xDrive35d doesn't sound as good as this though.

In the metal

It really isn't easy to tell the M40i apart from the regular X4 M Sport unless you know what to look for. As it's an M Performance Vehicle it gets Ferric Grey detailing, found on the door mirrors, front grille and new bumper. That's also the colour of the (optional) 20-inch alloy wheels, which are probably the most obvious model differentiator, along with a unique style for the exhaust outlets, one on each side of the new rear bumper. Strange to say it, but even those 20-inch wheels look a little lost in the wheelarches.

The interior is perhaps more successful, with a healthy sprinkling of M badging, including on the chunky sports steering wheel, the automatic gear shift lever, sports seats and door sills. The model name, 'X4 M40i', also appears on the instrument cluster. Otherwise there's little difference between this and the normal X4 variants, so occupants sit lower than in, say, a BMW X3, but higher than in a BMW 3 Series. There's loads of headroom and for four the X4 is comfortable. The boot holds an adequate 500 litres, though the rear seat back splits and folds to expand luggage capacity to a useful 1,400 litres.

Driving it

It must be said, the X4 M40i makes a great noise. No SUV should sound this good. That's thanks to a sports exhaust bolted to a turbocharged 3.0-litre straight-six engine that uses petrol, not diesel. Its output isn't far off that of the equally new BMW M2 and in spite of the extra weight there's not much in it in terms of straight line acceleration thanks to the X4's xDrive four-wheel drive system. A 0-100km/h time of less than five seconds for the X4 is impressive and the car feels fast at all times, more so if you switch into Sport+ mode. That results in a sharper throttle, less assistance for the steering, a quicker responding transmission and firmer damping.

The M40i comes with several items that are not standard on the regular X4 to alter its personality, such as Variable Sports Steering and Dynamic Damper Control (DDC). The former is a variable ratio steering rack, making the X4 feel more agile when the going gets twisty, yet more composed at high speed in a straight line. DDC allows the driver to select how firm the damping is, again with the aim to give the X4 the best of both worlds. We were impressed with how the chassis coped with fast driving down a bumpy and twisting back road. It even felt more rear-driven than other X4s do, adding to the enjoyment. Ultimately though, this is not how such a car will ever be driven and not all will be happy with the extra layer of firmness built into the chassis.

What you get for your money

We can't give the M40i a rating here as we have not got an Irish price for it. For reference, the X4 line-up starts at €59,081 on-the-road for the xDrive20d SE model and rises to €82,270 for the xDrive35d M Sport version. The M40i would be higher again if it was imported. Where it is sold, it comes with a generous helping of equipment, including a wide variety of exterior colours and interior upholstery and trim finishes. There are also Xenon headlights, Dynamic Damper Control, Variable Sport Steering, parking sensors all round, 19-inch alloys and a load of in-car technology too. As you'd hope for the range-topper.

Summary

We realise that the X4 M40i is an irrelevance to Irish readers. One: it won't be sold here officially. Two: if it was, nobody would buy it as there's just no demand here for a high-performance SUV that sips from the green pump. Nonetheless, car enthusiasts will be interested to know that the most focused X4 lives up to its M Performance Vehicle billing. It's the fastest and most engaging X4 money can buy (depending which country you live in) and it is a bit of fun, but we're not missing out on much when the six-cylinder diesel X4s do almost the same job.