Economic optimism rebounded sharply in September, with 47% of gas consumers saying that they were optimistic about the economy, the highest level of optimism in 14 months.

Optimism increased 8 percentage points from August's 10-month low of 39%, and also is 8 points higher than optimism a year ago (39%).  A majority of consumers ages 18-34 are optimistic (56%), as are consumers in the West (51%).

The 8-point increase overall in optimism was the largest recorded since January 2013 when the National Association of Convenience Stores (NACS) introduced its monthly NACS Consumer Fuels Survey to examine how gas prices affect consumer sentiment.

Nearly 9 in 10 consumers (87%) say that gas prices, which they report have dropped 20 cents per gallon over the past two months, have an impact on their feelings about the economy.

"We have seen increasingly wide swings in economic mood over the past three months as consumers continue to sort out how world and national events could affect their economic security. At the same time, it appears that what happens at the corner store with gas prices continues to play a major role with consumer sentiment," said NACS Vice President of Strategic Industry Initiatives Jeff Lenard.

As sentiment about the economy continues to swing haphazardly, consumers are divided on how sentiment translates into spending. While 22% of consumers say that they will do more shopping over the coming month, another 22% say that they will do less shopping. Not unexpectedly, younger consumers say they will drive any sales increase; 38% of those ages 18-34 say that they will do more shopping this coming month, compared to only 12% of those 50 and older.

While it remains to be seen whether optimism will hold or translate into spending, consumers say that they have tangible signs that they are getting more value for their dollar. Miles per dollar spent at the pump increased 2.3% to a six-month high of 6.8 miles per dollar, according to consumers' self-reported gas prices and gas mileage estimates.