I solved the problem, altough not the way you'd expect: I found and downloaded the original TDU - not Gold edition. So far in the not Gold edition 11 car delieveries, 10 perfect. Only one is still bugged - an olf Corvette (Stingray, I think), probably from the 50's. This car loses money as it goes.
And with the not Gold edition I also solved the other problem I didn't mention - manual shifting works, most of the time. Now I can decelerate a lot later than I had to with automatic transmission. The shadows are a little too dark
even with increased brightness but that's a small price to pay in order to have the other two things working. Also, the game won't close upon exit and I gotta kill its process, but I can live with that too.