Filling-up at the pump is getting more expensive, with the average price of a gallon of gas hovering around $3.55 a gallon across the Valley.
But some drivers are paying even more and don't know it.
CBS-5 News found several gas stations over-charging their customers.
Data obtained from the Arizona Department of Weights and Measures from the past year, showed widespread problems at Valley service stations.
One of the biggest issues is meter jump. That's when the price meter jumps from zero, charging the customer money before any gas is pumped.
The extra cost to customers can range from a nickel to 75 cents.
Another problem is meter creep. That is when the price meter and gallon amount are rolling, but no gas is coming out.
Here's a look at some of the worst offenders when it comes to overcharging customers through meter jump and meter creep.
* Fry's Fuel Center off Chandler Heights Rd. and Higley Rd. in Gilbert. Fined $1,800.
* Shell at Bethany Home Rd. and 67th Ave. in Glendale. Fined $1,800.
* Valero at Broadway Rd. and Gilbert Rd. in Mesa. Fined $1,800.
*Circle K on Main St. near Greenfield Rd in Mesa. Fined $2,400.
* Shell on Central Ave. north of Southern Ave. in Phoenix. Fined $3,900.
* Safeway on Baseline Rd. off 50th Ave. in Laveen. Fined $1,500.
* QuikTrip on Highland Ave. off 16th St. in Phoenix. Fined $2,700.
*Arco AM-PM at Gilbert Rd. and Broadway Rd. in Mesa. Fined $2,700.
*QuikTrip on Ellsworth Loop Rd. off Rittenhouse Rd. in Queen Creek. Fined $3,000.
* Shell on Central Ave. north of Southern Ave. in Phoenix. Fined $3,600.
Service stations with perfect inspection scores make our Dean's List.
* QuickTrip at I-10 & Miller Rd. in Buckeye.
* Circle K... at Power Rd. & Germann Rd. in Gilbert.
* Fry's Fuel Center off Baseline Rd & Power Rd. in Mesa.
* 7-Eleven store off Chandler Blvd. & 48th St. in Phoenix.
* Safeway off Waddell Rd. & 138th Ave. in Surprise.
* Woody's Food Store on Tegner St. in Wickenberg.
According to state inspectors, the fines vary depending on how widespread the problem is and whether the business is a repeat offender.
The best thing consumers can do is pay close attention and report any problems you see.
You can file a complaint at http://www.azdwm.gov/Dwm/PV/Complaint_LocationSearch.asp
Copyright 2013 CBS 5 (KPHO Broadcasting Corporation). All rights reserved.