In 2010 the Utah Transit Authority had an annual transit ridership (over all modes) of 36,507,282 rides and 221,880,786 passenger miles traveled (6.1 miles per ride).
Cities with robust bus networks see much higher ridership than they do in Oklahoma City.  The Salt Lake City metro area has a population of 1,123,712, which is only about 100,000 less than the Oklahoma City metro.  Salt Lake, however, has a much more extensive transit system that includes bus, commuter rail, and light rail.  In 2010 the Utah Transit Authority had an annual transit ridership (over all modes) of 36,507,282 rides and 221,880,786 passenger miles traveled (6.1 miles per ride).  Assuming the average fuel economy of the cars in Salt Lake City is 20 miles per gallon, we can reason that the region saved about 11,100,000 gallons of gas in 2010.  This means that Salt Lake City residents saved over $36 million on gas in 1 year.