Winter fuel blend is different from summer fuel. In addition to emission related issues, it has less energy per measure to give it properties that make it easier to start in cold temps. Takes more fuel [heavier foot] to get the same performance. Along with the other suggestions, try going at least to mid-grade. Check to see if your A/C compressor clutch is engaged. I personally don't go over 36 PSI in my tires for reasons related to handling. And ride comfort degrades too much for my taste. Driving habits have a significant effect on fuel economy such as letting it idle for long periods to warm up [the 30 minutes cell phone conversation mentioned is a great example], quick starts. If you carry extra weight in your vehicle remove unnecessary items. Differential lubricant ages and thickens.I switched to a synthetic and saw a slight improvement. At sea level in Scam Diego I get 22-24mpg city and 28-29mpg hwy at 65-70mph, A/C off, using a light foot in my 1988 245 wagon, automatic. My philosophy is if you just drive, expect mediocre economy, if you drive with the end of getting good economy in mind you can improve your mpg.