the cars pollute a lot more than they are supposed
Personal Opinion only, no facts to back up my views.:
Those cars should have the engines ripped out and less polluting engines replacing them. The are diesels, Diesel fuel is one of the major causes of autism, along with vaccines. Autism used to be a "Country" problem, not a city problem, until more and more busses that burned diesel were put into use, and then the rich people needing their special diesel mercedes benz cars burning diesel. Remember where Autism started where it was a problem, then where that problem moved to, and what fuel followed the trend. *Rip out the offending engines, and put something somewhat safer in them.
I think that VW has admitted that it has no cost-effective way of repairing the cars. They opted for buying them back rather than replacing the engines. I think I read somewhere that the buyback agreement with the court required the cars to be permanently destroyed.