It would be doable by car but I don't think its the kind of thing you should be contemplating doing if you don't already have some kind of experience of travelling in place like that.
The Oz bus or the train would be a much safer and probably even more enjoyable trip as you would have less to worry about.
If you really do want to do a massive road trip though somewhere like Dubai or Cairo would be much more achievable. Going to Thailand you would either have to go through the central Asian 'stans or Iran, Afghanistan/Pakistan and then Burma. Those are all dodgy place to be travelling cross country by yourself.
The Oz bus or the train would be a much safer and probably even more enjoyable trip as you would have less to worry about.
If you really do want to do a massive road trip though somewhere like Dubai or Cairo would be much more achievable. Going to Thailand you would either have to go through the central Asian 'stans or Iran, Afghanistan/Pakistan and then Burma. Those are all dodgy place to be travelling cross country by yourself.