PST on used cars bought privately are subject to 12% PST and no HST (as they have been for the past w years).
Cars bought from a 'dealer' are subject to 7% PST plus 5% GST.
No benefit to waiting to buy or sell a vehicle.
As a sidenote, I think the thinking behind the PST being set at 12% was partly to increase or maintain government revenue and, in what cheeses me off, to 'level the playing field' between the car dealers and individual sellers, after all, we can't have anybody being able to offer a better deal than the car dealers through a tax saving.