What is it?
BMW's largest SUV, but with a slightly more eco-tilt than most - uniquely for a mammoth off-roader, this sDrive 25d is only available in two-wheel drive. And that's rear-wheel drive, seeing as this is still a Beemer. As such, the CO2 emissions are 149g/km and it should average 50.4mpg. Impressive stuff for a near-two tonne SUV. It's also the cheapest X5, with prices starting at a relatively parsimonious £42,945.