FE with half tank of petro

[zpiloto]

Has anyone quantified any FE improvements with only filling the tank up halfway? I think there may be some benefit but am not sure how to test it. I can see where lighter car ( 8 gallons @7#)about 60# in my case, more fuel vapor in the tank, and with my heated fuel line recirculating to the main tank warmer fuel for better atomization. Any ideas on testing protocol? Also will operating with low fuel quanity shorten the life of the fuel pump? I drive mostly flat to rolling terrain city/highway mix.

[thisisntjared]

ive heard that your best highway mpg will be in the first half of your tank and if you refill when you get down to the half tank mark you will save 1 or 2 mpg. ive never tried this out though. it has to do with the surface area of the fuel and evaporation and the vacuum in the fuel tank.

[philmcneal]

i find i drive better with a full tank rather than a half tank. A full tank with 3 digit odometers can be very promsing!

then again i find the 50 pounds help me coast ;P

[SVOboy]

Dan only fills halfway in order to save weight, but I dunno.

Some insight drivers have noticed they get better mileage on a fresh, full tank, but they never came to any conclusions as to why.

[krousdb]

Yup, about 30 lbs. I just add as much as the SuperMID says that I used. After 9 of the 1/2 tanks, my fuel gauge after filling keeps getting higher. Today the needle fully cleared the half tank mark which means that the SuperMID is prolly over registering fuel useage and under registering FE slightly. Id say about 1/2 gallon over 2900 miles. So I might be understating my FE by about 0.6 MPG on any given tank.

I will do another calibration when I do a road trip. I just don't know when that will be however.