The BMW X5 eDrive is a plug-in hybrid that's designed to offer the same performance as the six-cylinder petrol or diesel versions of the popular SUV, but with better fuel economy and CO2 emissions.
BMW says the eDrive, which blends a 94bhp electric motor with a 241bhp four-cylinder turbocharged petrol engine, will bring around a 55% gain in fuel efficiency over a comparable X5 xDrive35i. The predicted combined fuel economy and CO2 emissions of around 74mpg and 90g/km will make the X5 eDrive a very clean large SUV indeed, given that the current cleanest model, the xDrive25d, emits 137g/km.
The eDrive can travel on electric power alone for around 19 miles; that doesn't sound like much compared with even some full EVs, but BMW's own analysis says that 80% of X5 journeys are less than this distance. A full pre-journey charge of the batteries would take between three and four hours on a domestic plug, or between one and two hours via a wallbox.
What's the BMW X5 eDrive Prototype like to drive?
Our brief drive in a prototype of the X5 eDrive revealed that the car is deeply promising. Performance is strong, smooth and refined in full EV mode, with no whine to speak of and, of course, the instantaneous torque from rest that electric motors offer. The pure EV mode works 'by default' at up to 42mph, but you can force it to run at up to 75mph - at the expense of range, naturally.
Perhaps the most impressive achievement, though, is the manner in which you can leave the system to switch seamlessly between the electric motor and the petrol engine. Just select one of the X5's driving modes and the set-up will tailor its priorities accordingly, focusing on maintaining (or even restoring) the battery charge, delivering out-and-out performance, or somewhere between the two.
BMW's engineers don't consider these prototypes the finished article at all, yet there's barely any judder when the combustion engine does kick in. Nor does the engine sound particularly loud or rough. The eight-speed automatic transmission (into which the electric motor is integrated, doing away with the need for a torque converter), offers smooth, rapid shifts throughout.
The joint output of the two power sources falls slightly short of their direct combined total, at around 295bhp, but that's still more than enough for rapid progress; BMW claims that with the electric motor providing a 'boost' function to the petrol engine, the X5 eDrive can crack 0-62mph in less than seven seconds; it certainly feels that fast.
The four-cylinder motor looks tiny in the X5's engine bay and it sits so far back that it almost makes the car front-mid-engined. There's a bit of extra weight overall - the hybrid is a little heavier than a normal X5, and the regular car is more than two tonnes as a starting point - but even with this in mind, the prototype doesn't feel any less composed. If anything, the positioning of the engine makes it particularly crisp on turn-in - and this on a car that's already known for unusual levels of agility.
The X5's eDrive systems also have an intelligent 'predictive' function; input a destination into the sat-nav and the car will analyse the route and then manage the balance of combustion engine and electric motor throughout to maximise efficiency. For example, it could use pure EV if your journey starts in town, then switch modes on the motorway to run on petrol engine alone and top up the batteries before reverting back to electricity for the final few miles of your journey in the next urban area.
It all feels like a bunch of different technologies - lithium-ion batteries and control software from the i3 and i8, combined with the car's ability to use navigation information and its surroundings to pre-empt key aspects of its operation - tied together in an easy-to-use package. You could drive the X5 eDrive for thousands of miles and never realise the amount of calculations going on in the name of fuel efficiency; this, in itself, is the car's cleverest trick of all.
What's the BMW X5 eDrive Prototype like inside?
Just as with the exterior - which looks entirely normal apart from an extra flap on the left-hand side where the charging socket is situated - you won't notice much difference in the X5 eDrive's cabin. It's pretty much the same as a regular X5's, albeit with the addition of an extra switch or two between the front seats to control the electric drive modes. You're likely to get blue kickplates on the door sills, just to remind you that you're in the 'green' X5.
More surprisingly, there's no major trade-off in boot space. Many hybrids suffer from much-reduced capacities because of the battery and electric motor installation, but the X5 eDrive's boot floor is only raised by around 2cm over the standard car. The engineers say they're working to ensure that the hard plastic load lip at the edge of the boot joins onto a completely flat load bay, and it looks like they're on track to achieve this.
Should I buy one?
You can't - yet. Even the project engineers admit that the X5 eDrive is 'around a year away'; if anything, we wouldn't be surprised if it doesn't arrive until it can coincide with the face-lifted X5, and that's unlikely to turn up until the second half of 2015.
However, there is considerable potential here. The X5 eDrive manages to offer the driving characteristics of smooth six-cylinder diesel and petrol engines, and the space and practicality of regular large SUVs, while returning fuel economy and CO2 emissions that wouldn't disgrace a supermini.
It's unlikely to be cheap, of course, but those ultra-low emissions could make this a seriously appealing option for company car choosers. It's still some way off, but we reckon this one could be worth the wait.
BMW X5 eDrive Prototype
Engine size 2.0 turbocharged petrol/electric motor
Price from tbc
Power Around 295bhp (combined output)
Torque 258lb ft (petrol)/184lb ft (electric)
0-62mph Less than 7.0sec (est)
Top speed tbc
Fuel economy 74mpg (est)
CO2 90g/km (est)