I've got a 2006 WM Caprice with 217,000 on the clock - ex chauffeur car. When I bought it, it had an intermittent fault code for the throttle position sensor, which used to affect gear changes, especially on light throttle. I replaced the throttle body/TPS unit ($300 brand new from EBAY vs $480 from Holden), and it's been fine so far. It also had a failed tyre pressure sensor, which I replaced, and no further problems with that system. Dashboard displays and DVD monitors all work OK. The only thing I've noticed is that the steering wheel 'trip' button doesn't always work (ie every now and then press it, and nothing happens - press again, and it works), and the power window switches can sometimes stick "ON" - tap them, and they go back to the neutral position. All in all, for the KM travelled, the car is in very good condition, and drives well. Engine is smooth, and still very economical. Everything still works. Prior to this car, I had a VY 25th Anniversary which we racked up 175,000 km on with very few problems, and before that, a VP Calais which we got to 360,000 km with very few problems before upgrading it.
If you've owned your car from new and look after it, it should last you well.