keep it as stock as you can and try to reduce some weight. A SRI and or CAI will only hinder your MPG. Just give the car a good tune up and then it's the human factor (have a light foot). For example when I drive from Albany to near Boston (162 miles for where I have to be) I shift at 2k and I drive from 65-70mph and receive about 41mpg; when I have my stock intake on I got about 43mpg (same driving style).