I don't understand the growing view that VW owners are likely to have a case against the car makers. It's all very different from PPI. 
Firstly, you'd have to have concrete evidence that you bought the car purely on the low emissions basis - correct me if I am wrong but there are cars out there with lower emissions than VW, so that argument could be shot down easily.
Secondly, any fines or financial liability is likely to be claimed by Governments, testing agencies, etc - although i'd want answers on how those carrying out the tests were defeated. There will be a clause or disclaimer in that which will have official backing in the view that they don't have to pay compensation to drivers beyond recall / replace / fix. 
Thirdly, how many actually own the VW models in question clear rather than them being financed by banks or leased? 
VW have clearly been up to no good, but i'm not seeing the margin for VW owners and drivers to launch huge claims. if someone can tell me where i'm seeing it wrong, happy days for the owners of domains like this.