Mileage Tax Because Our Cars are Too Efficient

I just heard on the news that Massachusettes is thinking about putting GPS chips in cars to track people's car mileage.  The idea is, as the cars get more efficient the amount of money that the state goes down because people aren't fueling up as much. 

Oregon already has this in place.  So now matter what we do, we are screwed.  My only reason for buying a fuel efficient car would be to save money on gas.  That idea is out the window if this idea catches on.  Forget the environment, if I am going to be charged for the amount of miles I drive, I am going to buy the biggest, baddest gas guzzling suv or 4x4 truck and enjoy every single one of those purchased miles!