BMW X5 xDrive40d

What is it?

Say what you like about the X5, but don't accuse it of being a flop. With production of the upmarket off-roader set to top the one million mark in June it's been hugely successful, continuously beating sales forecasts since the original's 2000 launch.

Now a subtle mid-life makeover of the current generation has brought it the potential for even more sales success, with some mild styling changes, minor chassis revisions, an extended list of options and, most significant, a second six-cylinder diesel engine.

What's it like?

You'll have to look hard to spot the styling tweaks, which include revised body-coloured bumpers along with new LED headlamps and tail-lights. It's not a lot, but given the popularity of the old model it seems smart not to go messing with the looks of the X5 too much. Step inside and the changes are even more subtle.

BMW has carried over all the existing engines to the new X5, but it's the new 302bhp, twin-turbocharged 3.0-litre diesel in the confusingly named xDrive40d that warrants most attention. Already available in a host of other BMWs, it is a gutsy device with a flexible delivery and excellent refinement ­ all of which makes it perfectly suited for duty in a big luxury 4x4.

The new engine's prodigious 442lb ft of torque arrives early in the rev range to make light work of the xDrive40d's considerable 2110kg kerb weight, endowing it with excellent step-off, solid in-gear shove and a good turn of speed.

An eight-speed automatic gearbox is standard and operates in a more decisive and intuitive nature than the older six-speed unit, particularly on downshifts, which are noticeably smoother than before.

Those extra couple of cogs maximise the 40d's cruising potential ­ 100mph is achieved at just 2500rpm in top gear ­ while modifications to the steering have made it more linear and better in a straight line.

Should I buy one?

At £46,310, the new xDrive40d is £2330 more than the reworked xDrive30d, but £8770 less than the only petrol model left in the UK line-up, the xDrive50i. Given its impressive blend of performance and economy, it's the X5 to have.

Rating: 9/10