CNG / Propane might be a way to go. There's alot less BS that goes into making CNG, since it comes right out of the ground nearly ready to use. So the price may stay lower. They also pollute way less. And Propane has an octane of at least 108. And your oil never gets dirty.
I'm converting to propane as soon as i get all the parts together. Not cuz it's cheaper, but it's easier to use with a turbo...
I don't know what it is with people here in the states and their giant cars. People here tend to lease these big expensive cars, so maybe enough $60 fillups and they'll opt for something smaller.
An A15 will get 20+ mpg with even the most poorly tuned weber at 80+ mph.