Your web site is great, really enjoyed all the novel ideas. Played with improving mpg over the years, tried many ideas, I did one simple modification that seems to have worked, but I have tried it with one car. My 1991 Civic with 200k miles, I wrapped an 3/8″ heating hose around my fuel filter, caused the gasoline to warm up, increased my fuel mileage from 34-36 mpg to 40 – 42 mpg. 10% increase for $12 of hose. If you have someone that is willing to try this technique, I would like to know if they have similar results. Also, I live in Wisconsin, this time of year (december – March) all vehicles mileage tend to drop a few mpg, for example, the above civic mpg before modifications dropped about 2 or 3 mpg, its now mid winter and the mph has remained constant at 40+ versus previous year mpg’s of 32-33. The EPA on this sedan is 35mpg when new!

According to that article… “[To] create smoother air flow, Ernie installed a homemade spoiler, improving fuel economy by 5-8%. Add low-resistance tires, low-friction engine oil, and a lubricious fuel additive (biodiesel), and you’ve got major increases in gas mileage.” Each one of these 4 techniques can be allocated a single bubble in my diagram above (Air Resistance, Rolling Resistance, Engine, and Fuel respectively). There’s a lot more that can be done than this article mentions. When I find time to post more in this series of I hope to tackle each bubble in turn and provide a comprehensive list of techniques that can be employed to reduce fuel consumption, with experimental results (and basic physics) to show how much improvement can be expected from each technique.

http://gas2.org/2007/12/12/how-to-get-76-mpg/

But I wonder how well they do when velocity is small.