What is it?
Volvo’s people call this XC90 a Twin Engine, but if they really wanted to be that pedantic, they should have called it a Triple Engine.
This is the plug-in hybrid version of the new XC90, Volvo’s large SUV, and it arrives in early 2016, about six months behind the D5 diesel and T6 conventional petrol.
Like those versions it has a four-cylinder, 2.0-litre engine under the bonnet. Here it’s supercharged, for low-rev response, and turbocharged, for higher-rev response, and is engine number one. It drives the front wheels through an eight-speed automatic gearbox.
Engine number two is the one at the back. It sits neatly within the rear subframe and is an 81bhp electric motor driving the rear wheels.
It’s powered by a battery pack stored in the transmission tunnel, where there’s space because, unlike in other XC90s, there’s no propshaft. Plugging in the XC90 charges the batteries.
How engine two delivers its power is flexible. You can choose to drive on electric mode alone, where the range will be 24 miles. Or you can opt not to use it and save the battery power for later. Or ask for maximum input. Or choose a specialist 4wd mode for best traction off-road. Or, as is most likely, just let it sort it out itself.
If you want to get pernickety, there’s a third motor: a 25bhp starter motor/generator between the petrol engine and gearbox. It’s not much of an engine but it does pitch in from time to time, to smooth the transition between the different drive methods and fill any torque gaps.