Gas prices at the pump rose slowly over many years until the 1970's when they really started to rise. But in 1980/81 they had an unprecedented spike.
There was a lot of unrest in the Middle East, OPEC actions, etc. There were even US citizens held as hostages in Iran, if you ever heard of that event.
Anyway, gas prices were a huge topic then. So this sign was topical albeit corny.