I see the biggest variances from temperature changes. Seems like when it's under 55* I drop a couple mpg. In my wrx I see 22mpg at 80mph. Dropping to 70mph brings it up to 23.5. At 60 it jumps to 25 mpg. If Subaru would have given us a .50 top gear it would help immensely. If I keep it below 2500 rpm I've seen 27mpg over a tank of gas.