I have been tracking my milage for the last 11K in the same fashion as Sam without the shaking part. I have an 08 hatch 5sp. I have consistantly got 31MPG over each entire tank of gas, not just a short trip. This is both highway and city. I noticed if I keep the highway under 70 and the rpms less that 3500 I get a little better. These are real world numbers.