It's not like east Germany had any secret super advanced technology to engineer or even invent cars that nobody else had. It was quite the contrary. Much of their talent pool, namely BMW (EMW) and Audi (Horch) engineers moved to the West. I call the East German invented Golf an urban myth maybe created by some East German inferiority complex or similar. They had talented engineers but they could not make much use of them. Consumer cars were politically considered non-priority and even East German made trucks were limited to smaller sized engines. The biggest permitted being the W50/ L60.
Here is one of the final "excellent" cars made by east Germany, the Horch designed P3 military Jeep.
https://p3-freunde.de/gelaendewagen-p3/
However the Soviet Union claimed to be the exclusive supplier of serious military Jeeps. DDR had to abandon this market.