i'm located in Utica, Michigan... are regular AC Delco plugs ok?

Here'* what I use
INTENSE-Racing.com: Autolite® Copper Core Spark Plugs

Close to me, but we have a small lake between us. Wish I could help you.

update...she'* still getting only 13 mpg. i told nichole to run premium only and that hasn't helped much. i also ran a bottle of injector cleaner through the car and nothing. i plan to check the plugs this weekend. how do i get to the oxygen sensors? how expensive are they?

well hold up a second do you know if you engine is a high compression engine if it is then you should be getting better gas milage with higher grade. believe it or not higher grade fuels burn slower then the lower grade fuels