(Garden City, UT) — The average price for a gallon of gas in Utah has fallen over the past week – but just by a penny. Statewide, the average price for a gallon of self-serve regular is now four-dollars and 20-cents. Triple-A says the most expensive average price can be found in Rich County where it’s four-dollars and 48-cents. Cache County has the lowest price at four-14. Gas is four-17 in Salt Lake County.