Car trip through Asia

I was thinking of doing a big tour (at least 2 months) through some Asian countries spring next year (probably from Cambodia through Vietnam and Laos and then a bit of China). I’d rather want to be independent while being there.
So even if maybe unconventional for travel in Asian countries, I thought of renting a car (or rather SUV or Jeep) would be the best to do this. Does anyone have experiences with the highway/road infrastructure in these countries? Are there automobile clubs to help me when my car breaks down?
Or do you think the whole Asia-By-Car trip is not a good idea? Maybe there are good train or bus connections?
I’d be glad about any advice you have for me!