decreasing gas mileage

things that can affect mileage: (1) tires and tire pressure- Michelin and very few others have low rolling resistance, which gives better MPG. lower tire pressure hurts MPG a lot. (2) gasoline- not the octane, but the brand. read about this at www.toptiergas.com also, some areas of the country are required by the EPA tp seasonally adjust the additives to gasoline to help smog. ask about this. (3) engine performance- synthetic oil, plugs, fuel filter all have an bearing on MPG (4) driving habits. jackrabbit starts, passing on the freeway, windows open instead of AC (5) age/mileage of vehicle