As everybody knows, buying a second hand car is a speculative experience. You really do not know what you are buying, nor can you realistically accept as truth the history of the car e.g. service, driving style etc.
Cars that have changed over over several times and often have fallen into the hands of the fabled 20-somethings with a lust for performance, mods and speed ... well, I would think cars like the VZ-VY would have been thrashed and trashed about and not given all that much attention to service. I'm not going to tar all 20-somethings with the same brush: I've known a number who have truly looked after everything imaginable, far beyond what a Holden techie would look at. But landing on a car that looks good is still speculative. If during the test drive (which should be done at urban speeds as well as freeway cruising to work the car through its responses) the car "appears" to be running well, move onto the next assessment: that of the service history. Any large gaps between services are often not adequately explained by dealers. Has the car had oil and transmission/clutch services at the required intervals (oil changes definitely no more than 12,000km for Alloytec engines, ideally 7,xxxkm if just urban driving).
A pretty face is one thing, but I look long and hard at the service history when scouting for cars, and try and by ex-fleet or Services. So what if they are thrashed, at least they are serviced properly! Friends have ex-Police, CFA cars (sedans and wagons) bought years ago and still in excellent shape.
Be aware that older cars will have emergent problems e.g. starter motor, fuel pump, brakes ... all of which can cost a lot of money sooner than one expects. Hedge your bets and look for a car with lots of history and sensible driving.