On the road the XM never feels quite as enjoyably rapid as you’re expecting, which is manifestly un-M.
But the comparative lack of practicality, the obstinately ugly aesthetic and the punchy asking price are all okay, because the XM redrafts the dynamic rulebook for fast SUVs, with M5 CS genes palpable in its very DNA, right? Wrong. And unfortunately, this is down to not just one key weakness but several.
For one thing, BMW might be weltmeister when it comes to disguising weight in performance cars, but the XM is a bridge too far.
It weighs an epic 2710kg. The full-size Range Rover P510e (that’s the similarly V8-engined PHEV one) weighs only 15kg more.
Part of the reason for this is that the XM is built on BMW’s modular CLAR architecture. Being versatile and torsionally very stiff makes the CLAR heavy. It’s why the M3 weighs a lot more than even the Lamborghini Aventador.
With the XM, there’s then the extra weight of the electrified bit of the powertrain and the additional bracing that any M SUV needs. Add in the luxurious interior and wheels that measure up to 23in in diameter and you have an extremely heavy car.
It shows in the figures: 4.3sec is quicker than anyone needs but isn’t 644bhp quick, especially with torque fill being injected off the line.
It is an entertaining powertrain, at least. In the default Hybrid mode (there are others for electric-only and battery hold), the XM sets off more or less silently before – precise moment dependent on throttle position – the V8 explodes into life with zero latency and calculated ferocity.
Both the engine and the motor have their own sonic signatures, and when the two combine, there’s something otherworldly and quite exciting about the XM. It’s just a shame that the fine-tuning isn’t there.
For a heavily blown unit, this V8 loves to spin out, while the motor ensures the throttle is always alert to inputs, but the roll-on response from low speeds is inconsistent, which is exactly the opposite of what you want in such a hefty and powerful car.