Well, I have two tanks under my belt after installing the airtabs. So far the average for my last 3 tanks BEFORE installing the airtabs was 48.9 mpg. My two tank average AFTER installing the airtabs is now 50.8 mpg.
That works out to an approximately 3.8% improvement. By "tank", I mean a fill. Typically I take on about 10-11 gallons whenever I fill up. Now, of course, we all know how unreliable a one tank calculation is since I'm subject like everyone else to air pockets in my tank, how many "click off's" past the first auto shut-off I dispense, etc. So, even though I try to control as many factors as possible when I fill up, I feel more confident with a larger data set like several tanks worth before I break out the champagne thinking I've improved my fuel economy.
At this point, I'm somewhat more confident in saying that the airtabs do improve FE. I've previously reported in this thread how they are definitely keeping my rear window and hatch cleaner. However, I'd like to get 5 tanks worth of experience before I'm really convinced. It is suggestive that the 3.8% improvement I'm showing so far is about what the company quotes on their website.
Someone may suggest I take them off and continue the experiment by gathering an additional data set sans Airtabs. I'm not planning that because peeling off each airtab, even though it can be done (I had to trash a couple because I made mistakes during the installation), does ruin your chances of getting it back on. The adhesive tends to peel the backing off of the airtab body, so it's kind of a "once it's on, it's on" kind of a deal.
As far as the driving techniques, I do mild hypermiling. Tires are at 45 psi, gentle acceleration, glide whenever I can, anticipate traffic flow to avoid using my brakes, combine errands so as to avoid short trips, stay at 55 mph in far right lane on freeway, avoid the A/C. I don't draft trucks or turn off the ignition (FAS) though.
