Have you ever deviated from the stock engine and components? I mean it! Air filter, plugs etc.??? If you have, you will get less mileage. How I get 20 mpg in summer is simple. No engine change items. (Tried a K&N air filter once and watched mileage plummet...really!) In winter, I run higher tire pressure due to lower ambient temperture not causing over inflation. Take the roof rack off, not only quieter but better mileage. The old addage more HP=less mileage is true. Stick to 215hp. Also, synthetics in drive line and engine cut resistance and boost mileage. That's all for now, I'll think of more later.