I thought we long broke the 1980's adjusted price for a barrel of oil. The media said it was around $80-$81 a barrel. Of course, that was when oil was reaching $65+. When it hits a sustained $90/barrel the 1980's adjusted price will be $110/barrel, and so on... I do believe around $3.50/gal was the price point match as well.
I like a multi-faceted approach to this "crisis." Bio-Diesel, Ethanol, Hybrid (gas, diesel, bio, and ethanol), pure electric, and hydrogen. H2 is further off because of infrastructure issues. We can't rely on just one "fuel" anymore.
Problem is that I can't say, let's all go to Bio-Diesel. There is not enough oil crop or waste oil to make enough of it. Plus, growing for fuel raises food prices, which raises the price of the food. We are already starting to see this with ethanol.
Jut my .02 -
I think that $5/gal is the tipping point for most people to change their car buying and driving habits. It will force the "people" to buy more fuel efficient vehicles; therefore forcing the manufacturers to create more fuel efficient models. I know that I will rethink my driving vacations when gas/diesel is $5/gal. and flying is already too expensive for my family.