According to EPA estimates, a 2010 Pontiac G6 gets 22 miles per gallon in the city and 33 miles per gallon on the highway. This yields a combined 26 miles per gallon.
This corresponds to an estimated fuel cost of $2,100 per year at 2014 gas prices although this figure varies depending on how much one drives and how much of that driving is in the city. In general, later Pontiac G6 models get better gas mileage than earlier models. For comparison, the 2005 Pontiac G6 gets an EPA-estimated 19 miles per gallon in the city and 26 miles per gallon on the highway. Although the difference in gas mileage appears small, it adds up over a year of driving.