It won't matter, those who can afford the gas will still line up in drive-Thru's waiting for their cup of coffee idling their vehicles 
Maybe it's time to reconsider the size of personal transportation, why can't an inexpensive size smart vehicle be mass produced that can accommodate 1 or 2 ppeople because that's all I see in my work commute these SUV behemoths stuck in traffic with one person in them. A car priced 10k only and please don't mention a Nissan Micra, the government can give incentives to purchase instead of those Tesla's that only a few can afford.