I've brought a few back to Can. and as long as you do the paper work pay the taxes there is no problem. When our dollar was good a lot of peolple were bringing cars back and some were trying to save a few bucks on taxes by saying they paid less then they really did. They got smart at the border and would check into them it, if you got caught lying it could get real expensive.
I found the best way was just tell the truth and make sure my forms were at the border 72 hours before I crossed like they want.