you used to be able but as mentioned previously borders closed at present. You also need a car ‘passport’ from the local car registration authority and a T sticker. Remember they drive on the wrong side of the road outside Thailand !!!
Ship it through an Agent to China. Pay duty there yjen ship to Thailand. No duties on Chinese imports. You may be able to buy a container for around $800 and get Evergreen or Maersk to ship it for you on volume basis.
It’s very unlikely. They are desperate for tourism money again and they have a hell of a lot of expensive PCR tests, hotel quarantine rooms and hospital beds that need paying for!!!
I have also tried the "so 1 is 4500 baht how much if I buy 100" trick. OK I will buy 1 now and if its OK I will come back for the other 99. That went down better in the middle east Souks though.