The price of gasoline is influenced much more by political and economic factors than anything else. And I really don't see a long term trend in gas prices. Five years ago the price was lower than it was in 1970 even BEFORE the Arab oil embargo.
Yes, but the oil companies were losing their shirts at that time. It was not sustainable. If you want to look at the trend, you need to factor out the time periods when the market was not operating at a sustainable level. One of those was in the 90s.
The other thing you need to do is look at the price of oil, not the price of gasoline. The price of gasoline is heavily influenced by the refining industry, which has its own issues. An increase in the efficiency at the refinery level could mask a trend.