New diesel engine addresses our biggest criticisms of the XC90, but we must wait for the new auto for a definitive judgement.

Hell has frozen over, a pig is fluttering past my window, and the DSC light on the dash is flashing. Yes, the diesel XC90 – formerly fare game for hard-charging Smarts – now has enough beans to trouble its traction control in tight corners.

The reason for this new-found punch lies beneath the revised engine cover, the only visual difference between new and old D5s. It’s the same 2401cc five-pot, but its Garret turbocharger features a larger compressor rotor and curved vanes to improve gas flow. There are more injectors, larger combustion chambers and a standard particulate filter too. The result is 185bhp (up 23bhp) and 295lb ft of torque (up 44lb ft).

New electronic glow plugs result in a less chuntering startup, and from idle more precise injection brings a noticeable NVH reduction. It’s not in the same league as the Discovery or new Mercedes ML, but refinement is much improved.

Off-boost the D5’s small capacity still struggles with its weight, but past 1500rpm it feels lively, and much keener to rev to the 4500rpm redline. It’s also a touch more agile, the revised Haldex coupling giving more rapid transfer of drive to the rear when needed.

Prices are up by £1540-£1690, and there’s a slight increase in fuel consumption and CO2 output, but benefit-in-kind taxation is down three per cent thanks to Euro IV compliance.

Unfortunately at launch only the six-speed manual was available, a transmission that accounts for just three per cent of XC90 sales. The definitive verdict will come in October with the new six-speed Aisin-Warner auto.

When we last tested the XC90 our biggest bugbear was its ineffective drivetrain. While it’s still not a class leader, the new D5 closes the gap to its six-cylinder rivals and lets the XC90’s other attributes - looks, versatility, comfort, quality - shine through.

Alastair Clements

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