Ever since BMW decided to invest heavily in its M Performance models, they’ve given BMW customers more difficult decision to make than ever before. It used to be that M cars were the most desirable but M Performance cars have offered customers another choice. For the most part, M Performance models and true M cars actually share a lot; from the size of the engine, to their architecture and the technology on board. The differences lay in the way the cars drive at the limit and how fast they are. That’s why a car like the BMW X4 M40i might make a lot more sense than its X4 M brother.

The video below shows us just how fast the X4 M40i is in a straight line. Under the hood hides a 3.0 liter straight six B58 engine making 360 HP (European version) and 500 Nm (369 lb-ft) of torque, a powerplant that’s known to actually have higher read-outs on the dyno. That mill allows it to reach 100 km/h in 4.7 seconds according to this video and then double that speed in an additional 13 seconds.

That is plenty fast and 90 percent of the people won’t ever need more. The truth is, unless you live in Germany, you won’t ever keep the pedal pressed all the way down for more than 5 seconds, unless you want to lose your license. If that’s the case, is there truly a need for an X4 M? Well, yes and no. The X4 M is definitely more agile and a lot sharper than the M40i. It’s also faster by quite a lot and more powerful.

The thing is, that extra sharpness comes with a big caveat: stiffness. Having driven the X3 M Competition earlier this year I can tell you that it’s one of the stiffest cars I’ve ever driven and the stiffest SUV I ever had the chance to sit behind the wheel of. It’s no joke and yes, it will deliver on track but unless you buy it specifically for that, using it on public roads might be a bad idea. Therefore, the decision is, as usual, yours: get yourself a decently fast car or get an even faster one but get ready to have your spine examined more often.