[brucepick]

Good on all the work you've done so far. With EPA Highway of 17 and you're getting 20.5 approx, that's a really good improvement - more than 20% above EPA already.


I think aero mods are definitely going to help you. I'm guessing that in Texas you do lots of highway miles, 60 mph and above. I got a lot of benefit from my belly pan on the Civic, and most of that benefit seemed to come from the front section between bumper and firewall. The planned wheel covers are a good idea.

Think about a tapered cap, one that gets shorter at the rear. I saw some discussions and pics of those in the Aerodynamics subforum. Should be pretty easy to build one that actually helps your aerodynamics. If you want to make it look cool or macho, you'll need to tackle that separately.

Oh yeah - tires. If yours are knobby off road capable ones, consider tires with a smoother highway tread. And in any case, air them up to the max imprinted on the sidewall. And check pressure often.

Mostly we find that better flowing intake and exhaust don't help fuel economy a whole lot. They improve the max power output you can achieve, if the original provided some restriction. Remember, you're likely only using a tiny percentage of the engine's available power. At the low throttle levels used in hypermiling, the amounts of air in and exhaust out are far below the capacity of even a bone stock system - in my humble opinion, of course. Three inch pipes can help at wide open throttle at max rpm. You're likely at 1/3 throttle and 1/3 max rpm most of the time, so 1/3 * 1/3 = 1/9 of max/max air and gas flow. Am I close in my guess?