[LocoJason]

Thanks guys,

I will post my testing method as well as the spreadsheet I have been building in due time. My commute is over 20 miles largely without traffic and only two stoplights, which makes it pretty good for testing changes.

I also 'tested' a hot air intake on a trip last month, which was very easy to do on the focus by moving the fresh air duct down behind the radiator. This was not an ABA test, but on a 90 degree day the intake air temps jumped from ~98 to ~140. Ignition timing at the same load was about 2 degrees lower (27 vs 29btdc). No notable difference in fuel economy compared to the last trip up there (35.1 on both trips), but a notable power loss. Only one tank (400 miles) was burnt in this condition driving 70-75mph all highway to Michigan. On the way back (back to stock 'cold air' configuration) I managed 1.5mpg better, due largely to filling up with non-ethanol fuel while in Michigan.

Thanks for the link to the tire compatibility chart. The tires I have now are nearly new Michelin primacy MX4V in 195/50-15. They are supposed to last at least 50K miles, so I doubt I will be buying new/LRR tires any time soon. I wish I had a set of wheels/tires so I could test the effect of gearing changes though.

Not wanting to sacrifice power or make large investments for a small return in fuel savings, I'm looking mostly at aerodynamic improvements. I think between a passenger mirror delete, more under-panels, and some sort of rear airfoil I could get a 5%+ improvement.