I feel like this would have the opposite effect. No one will offer insurance against this liability at a reasonable cost. Instead, car manufactures will offer

I feel like this would have the opposite effect. No one will offer insurance against this liability at a reasonable cost. Instead, car manufactures will offer a guarantee that the car will not break emission standards when they sell the car to the consumer. This guarantee will be void the second you do anything the manufacture doesn't approve of, such as missing a scheduled servicing appointment, which of course must take place at the manufacture certified servicing center. Car manufactures will take the opportunity to lock down the firmware even further and block 3rd party servicing centers.