I'm intrigued by the VW car doctoring scandal. A squillion vehicles need to be recalled or at least rewired all across the world because they've been fitted with cheating software. What is the problem and what is the best solution? Firstly, changing the software on the car's engine management system will not alter how it runs, it won't be any more or less green, so I doubt that it's in anyone's interest, innocent VW owners and innocent VW dealers to try to cowboy these cars back into compliant shape; way too much effort and trouble there. The answer, as far as this low grade ex-coder is concerned is simple. You don't fix the cars, you already know that they are designed to lie and you know the parameters of the lie, you (well VW) know what they coded in to fix the figures so you have a baseline.
The solution is really to do nothing, leave the cars alone and let them run till they need a check or MoT or whatever. What needs to change is the equipment that tests the emissions. It needs a patch that counteracts and adjusts the actual readings to take into account the false figures. Once that is recalculated you will have numbers that are meaningful. The software is still lying but the reader knows the extent of the lie and adjusts for the lie to provide the true result. Of course that needs to be rolled out to all the test equipment but that's a lot less work that bringing the cars in prematurely and screwing with them, in my humble opinion. There you go, just saved VW £££s and their unfortunate owners and garages a whole lot of time.