In the US, with Lexus and Porsche chief among its rivals, luxury and performance rate as highly as efficiency, so the plug-in hybrid X5 gets plenty of surge to go with its zero-emission waft.
Consequently the car comes with a 111bhp electric motor located just upstream of its eight-speed Steptronic gearbox, and, ahead of that, the most powerful four-cylinder petrol engine in the BMW range: the 242bhp TwinPower turbocharged lump found in the 328i.
Total system output is rated by its maker as 309bhp and 332lb ft, and 0-62mph ought to take just 6.8sec. Claimed combined economy, mwanwhile, is 85.6mpg.
One of the advantages of the compact hybrid powertrain is that it allows the X5 to retain its standard clutch-based all-wheel drive system - and while there’s a lithium ion battery to find space for beneath the boot floor, most buyers won’t notice the loadspace sacrifice.
From a domestic socket, the car will recharge itself in a little under 4hr, or 2hr 45min if you’ve stumped up for the fancy-looking BMW i Wallbox.
What's it like?
From rest, the X5 is all noiseless grace and glide. Like most PHEVs, inertia is typically overcome by the electric motor alone, its effortless gust of instant torque being far more suited to the job.
BMW i-drivers will recognize the sleek dispensation of thrust - but they will be unaccustomed to its obvious limitations. Where the i3 and i8 seriously scamper in silent running, the much heavier xDrive40e (at least 150kg heftier than standard) settles into a more functional progress.
Insist on accelerating for all it’s worth in the all-electric MAX eDrive setting, and the car will eventually hit 75mph, although by that time you’ll be draining the battery at a predictably furious rate.
Without firing up the combustion engine, the X5 is limited to about 19 miles - and one imagines BMW recording that at a very gentle clip. For most journeys, and to get the best of the xDrive40e, the default AUTO eDrive hybrid mode is recommended.
Typically, the key to a PHEV’s performance has been the successful integration of petrol and electric motors - but as both here feed directly into the gearbox, there isn’t a great deal of driveline flounder with which to concern yourself.
Certainly you’ll register the introduction of the engine (an event marked by the spasmodic flick of the rev counter needle) yet the actual pause in progress is negligible and the accelerator pedal consistent.
Of more significance is the point where the control unit decides the electric motor needs help. BMW claims 44mph as the point where the power sources mingle - and that’s true - but only if your throttle inputs remain well toward the gingerly end of the scale.
Register the merest hint of commuter-style impatience and the X5 will immediately have its petrol-fired components enhancing the motor’s modest 184lb ft.
That the super-smooth four-pot does most of the heavy lifting isn’t unusual given the continued emphasis on performance, but clearly it isn’t aiding economy. BMW admits that a mixed-use 37-mile commute with a fully-charged battery will essentially cut the combined claim in half at "no worse than" 43.5mpg.
Over double that distance our test car averaged around 36mpg. Spend most of your time on the motorway, using the petrol engine exclusively in the SAVE battery setting, and you can expect to lop an additional 10mpg off that.
Should I buy one?
Compared to the xDrive40d - the X5 model the hybrid is clearly rivalling in price, performance and prestige - those figures start to look decidedly flimsy. But inadequate middle to long-range thirst compared to a diesel-engined stablemate isn’t surprising; for most UK buyers it will be the appeal of cutting the 40d’s 157g/km CO2 emissions almost exactly in half that might prove tempting.
The surprising thing - considering BMW’s compelling start elsewhere - is the extent to which the X5 has been gazumped even before it arrives in November. At 77g/km, not only does it fail to qualify for the government’s OLEV grant or evade the London congestion charge, but it also won’t hit the latest 5% BIK rate. Or even the less stringent 9% rate for cars up to 75g/km.
The new Audi Q7 e-tron will. And the imminent Volvo XC90 T8, after some furious recent fettling, will apparently manage 49g/km. That both are doubtless taking advantage of the well-known shortcomings in the current testing regime is for now beside the point.
By failing to set the efficiency standard, or really advance the segment in any way that feels relevant from the driver’s seat, the X5 - as refined and as comfortable as it is - falls short of the high bar set by BMW’s own endeavour.
Expect future core brand prospects such as the incoming 330e to reset that advantage, but for now there’s no compelling reason for the xDrive40e to stick long in the memory.
BMW X5 xDrive40e
Location Germany; On sale now; Price £51,845; Engine 4 cyls, 1997cc, turbocharged, petrol, plus synchronous electric motor; Power 309bhp; Torque 332lb ft; Gearbox 8-spd auto; Kerb weight 2305kg; 0-62mph 6.8sec; Top speed 130mph; Economy 85.6mpg (combined); CO2/tax band 77g/km, 13%