If you ever had an idea to import your car to Thailand, the best advice is to forget about it. There is a mountain of paperwork to complete as well as import tax that can be as high as 328% of the cars actual value.
If your car is worth US $50,000, the tax would be US $164,000.
As you can see, to import your car to Thailand if financially not worth it.
Plus, even if you could, you might never find any spare parts!
Visit the link Import a Car to Thailand for all the details.