You should get around 15 miles to the gallon. You figure gas mileage by taking the miles driven and dividing it by the gallons of gas used. In other words, 250 miles driven divided by 25 gallons would be 10 miles per gallon. If you are in this range, then you need to consider a tune-up, which involves plugs and wires. Also, if there is a performance problem, then you need to consider having the catalytic convertor checked out.
General Manager, Edgewood Parts