Gas prices are driving up the federal government's key measure of inflation, the Consumer Price Index. The CPI rose 2.7 percent in 2009, thanks largely to a 53.5 percent increase in the cost of gasoline over the last year following a 43.1 percent decline in 2008, according to CNN . This year, gas prices could be headed back to $3 a gallon for the first time since 2008 (the same year Denver hit its record of $4.01). Right now, prices at Denver pumps are inching back up, averaging $2.52 a gallon for regular unleaded fuel. That's up by 12 cents compared with a month ago, notes The Denver Post , citing AAA. Moreover, gas prices are at a seasonal low and typically rise around summertime, says Jeff Lenard, an analyst with the National Association of Convenience Stores. Meanwhile, Denver comes in at number 24 on the Daily Beast's roundup of "America's 75 Worst Commutes ."