What's all this about?

After a few previous flirtations with electric power, BMW is turning the X5 into a proper, plug-in hybrid vehicle (PHEV).

And what will it be called?

The X5 xDrive40e, signifying that it's all-wheel drive and, er... electric. Obviously.

So what makes up the drivetrain?

There's a 2.0-litre TwinPower Turbo four-cylinder petrol engine, supplemented by a synchronous electric motor integrated into the X5's eight-speed Steptronic automatic transmission. A lithium-ion battery pack sits under the boot floor, meaning the xDrive40e can only be had in five-seat configuration, whereas other X5s have the option of a third row of seats - although that does mean plenty of cargo capacity as a result, running from 500- to 1,720 litres depending on which chairs are folded away.

What power does this PHEV kick out?

The petrol unit delivers 245hp from 5,000- to 6,500rpm and 350Nm between 1,250- and 4,800rpm, while the electric motor adds 113hp at 3,170rpm and 250Nm from the second you depress the accelerator. System maximums are, as with many hybrids, a little lower than the combined figures, at 313hp and 450Nm, but that's still an impressive level of oomph. It means the X5 xDrive40e can go from 0-62mph in 6.8 seconds and is limited to 130mph flat out. It can also run in pure electric mode, where it has a 19-mile range and a 75mph limited top speed.

Never mind performance, how much will it cost me to run?

Not a lot. Its quoted fuel economy figures are either 83.1- or 85.6mpg depending on which alloy wheels you fit, while battery consumption is 15.4- or 15.3kWh/100km (62.5 miles). Emissions are comfortably in the 'free VED' zone, at 77- or 78g/km. A three-mode 'eDrive' switch is added inside, allowing you to run the drivetrain in hybrid mode (Auto), full electric (Max eDrive) or in petrol-only to maintain or charge the battery (Save).

You mentioned optional wheels - what's the rest of the spec like?

Pretty good. The xDrive40e can be optioned up with everything offered on a normal X5 (save for those two back seats), so toys such as Active Cruise Control, Night Vision, Head-Up Display and Active Suspension Package Dynamic are on the lengthy additional extras list. Standard kit includes BMW Professional navigation, 18-inch double-spoke alloys (19s and 20s also available), dual-zone climate control and Dynamic Damper Control with self-levelling rear air suspension.

How will I spot one on the roads?

Look for the charging point on the front-left wing, subtle 'xDrive40e' badging on the wings and similar 'eDrive' tags on the boot, plus twin trapezoidal tailpipes. There are blue flashes on the centre console and on the door sills, although to see those you'd really need to be friends with someone who owns an X5 xDrive40e, as barging into a stranger's car just to check if it's a hybrid might seem a bit odd.

When will it be on the road?

Backed up by the suite of hybrid-specific products and customer services that BMW rolled out for the i-branded cars (i.e. BMW ConnectedDrive and BMW 360o Electric), the X5 xDrive40e will be going on sale from autumn of this year.

Matt Robinson - 14 Mar 2015