Hi Garry,

The XC90 is pretty reliable, but you need to check that the cam belt has been changed every 130,000km or eight years, listen for knocking or squeaking noises over sharp bumps that mean the suspension top mounts need replacing, check for a rumbling or droning noise that means the rear wheel bearings are shot and budget for brake maintenance as an XC90 can go through a set of pads in 30,000km and a set of discs in just 65,000km. 

If it's a four-wheel-drive model make sure you get it inspected to see if the Haldex-supplied clutch based system is working properly - the centre clutch burns out easily and there's no warning light for it and few symptoms.