Actually, the price of gasoline six years ago (that would be January, 2008) was around $3.10. It got pushed up to $4.12 midyear 2008 by hedge funds and other traders, then plummeted to that low level you mentioned towards the end 0f 2008 AS THE WORLD ECONOMY COLLAPSED. You know that, I know that, probably everyone on this message board above the age of about 25 knows that, yet you choose to blame that on the bad old environmentalists. That's disingenuous at best and dishonest at worst. The current national average price for gasoline, which is around $3.30 per gallon, is essentially the same as it was six years ago, adjusted for inflation.
Here's the retail gasoline price chart if anyone wants to see it.
Barring another economic collapse, cheap oil isn't coming back. Know why? Because the new oil finds, such as tight oil from fracked fields, tar sands, and oil from deepwater wells is expensive to produce. Crude goes below $80 per barrel, those types of oil stop getting produced.