Do you mean importing a car TO Thailand?
If that is what you mean - let me give you some advice.
When I first became involved with Thailand I started looking into getting my car/motorbike there. I could write for hours on the subject but to put it simply - forget it. They use their own valuation if its not available in Parker's guide. Even if you are prepared to pay the 200% + of the valuation that you will be charged, your problems will not be over. Your car is likely to be impounded on arrival for some spurious reason and you will no doubt have to pay a hideous amount of money to get it back. Even if you pass those hurdles you will then have to pay 100,000 baht to register it.
Believe me, unless you are very well connected in Thailand, it ain't happening. There are some seriously well connected Thai's who's cars have been impounded and finally auctioned off. I also know one Brit who thought he'd met a customs official that could 'help' him - they could, for 1/2 a million baht - his E Type ended up going back to the UK.
I've given up on the idea.