The combustion engine is mated with a disc-shaped electric motor mounted within the housing of the gearbox. Produced by long-time BMW partner, ZF – the same company responsible for the new SUV’s standard eight-speed automatic transmission – it delivers 94bhp and the same 184lb ft as the unit employed in the upcoming i8 sports car.
BMW isn’t giving all the secrets to the X5 eDrive away just yet, but it suggests the combined system output will be more than 270bhp and 332lb ft. By comparison, the existing X5 xDrive35i’s turbocharged 3.0-litre in-line six-cylinder petrol engine delivers 302bhp and 295lb ft.
Energy for the electric motor is provided by a battery sited beneath the floor of the boot, which has been raised by 20mm over that of other X5 models to accommodate it. The lithium ion unit consists of cells supplied by SB LiMotive, a joint venture operated by Samsung and Bosch, and is claimed to possess a capacity of more than 9.0kWh. It can be charged either via a 400 volt wall box or standard 240 mains through a socket hidden beneath a flap within the front driver’s side fender panel.
What's it like?
Very good. The ability of the high-tech driveline to overcome the additional weight brought on by the electric motor and battery pack is evident from the outset.
Provided there is sufficient charge in the battery, the initial movement from standstill is achieved on the electric motor alone. However, it doesn’t take too much of a nudge on the throttle before the petrol engine chimes in to strengthen the initial acceleration. Together, they provide the X5 eDrive with thoroughly convincing step off and in-gear performance.
Despite weighing in the region of 2300kg, it accelerates with all the enthusiasm of the 2145kg X5 xDrive35i on a pegged throttle, as evidenced by a claimed 0-62mph time that BMW puts at "under 7.0sec". With drive channelled permanently to all four wheels via an electro-mechanical multi-plate clutch and an electronically controlled torque vectoring system, traction was never in doubt in the early prototype we drove.
Drive at a steady pace and the X5 eDrive impresses with effortless qualities. Despite our limited time behind the wheel, there is little doubt that it will probably be a decent long-distance proposition, aided by subdued driveline noise and silken gearbox traits.
An energy management system allows the driver to choose between three different driving modes: Eco Pro, Comfort and Sport.
In Eco Pro mode the electric motor plays a largely passive role during hybrid running without the ability to boost performance, while a coasting function is activated when you back away from the throttle to decouple the combustion engine from the gearbox to reduce mechanical drag and extend momentum. In the default Comfort mode the electric motor is used to boost performance when required, with a recuperation function activated to recover kinetic energy on a trailing throttle. In Sport mode, both the electric motor and combustion engine are continuously engaged, while the action of the recuperation system is made more aggressive with added retardation for additional energy recovery.
A button on the centre console also allows you to switch to pure electric mode – but only for a limited distance. BMW claims a zero-emission range of up to 18 miles on a fully charged battery at speeds up to a limited 75mph. It doesn’t sound like much. However, internal BMW studies reveal up to 80 per cent of journeys undertaken by existing X5 owners are of less than 18 miles, suggesting it will be more than enough for the majority of prospective customers.