why don't want to import car?

Hi there,

A strange quesiton... Read lots of posts in this forum that people don't want to import their cars to Canada when landing. Could anyone tell me why? What's the downside of doing that? I heard if you don't put the car in your "Goods in Possession" list, you will have to pay import tax nest time. It's like one-time deal (tax-free) only when landing. Is this true?