1) We only show one data point for the aggressive mud tires as we only started logging mileage on the last tank that was used with them on the Jeep. All previous tanks under both Cappa and Trasborg showed between 180 and 210 miles for about 17 gallons of gas. So, this mileage number is actually higher than what we were likely seeing.
2) The Pro Comp Extreme ATs are used as the baseline for the fact that we didn't have enough data points with the Nittos, and for the fact that the ATs stayed on the Jeep all through testing
3) Aside from swapping rear bumpers there were no modifications made during testing. The rear bumper weight varied +/- about 50lbs.
4) In our "average MPG of the second chart, we took total miles driven for a given test, and divided by the total amount of fuel used. This was done after testing was completed. The MPG numbers in the main chart were calculated on the fly as we filled the Jeep. Later, we realized that totaling the mileage and fuel consumption would be more accurate to calculate average MPG
5) Where we had enough data points, we removed the highest and/or lowest from the calculations. This happened only with the acetone. One 4/07 and 4/08, we removed those data points not because we had a lot of information, but because we were fighting a headwind through the Mojave Desert, and were reduced to 300 miles of 4th-gear, 3500+ RPM just to maintain headway on the highway.
6) Many of the lower points are where we had the Jeep off-road. However, we didn't specifically mark down when we were wheeling, so those data points stayed in. It is likely that without them, we would have shown a greater overall mileage gain.
7) In the Magazine, we talk about statistically significant. We don't feel that anything less than a whole mile per gallon difference was really enough to mention. Of course, you can clearly see that we lost .8 Miles Per Gallon with the Tornado in a month of driving (1261 miles), but since it didn't hit that magic 1MPG mark, we didn't mention it. While we did feel the difference, there were some (such as K&J) that we lost mileage, but didn't think it signifigant at all. From tank to tank, a 2 MPG swing was often noted... .04 MPG is nothing.
8) You might be wondering how we could keep the amount of fuel the same. Well, we tried to always fill the Jeep when the gauge hit the middle of the red zone (halfway between E and 1/8 tank) and we always filled it until we could see gas in the filler neck. Many a gas station attendant flipped out on us, as filling it that much usually entailed from 1-2 gallons of "topping off" which, for some reason they don't like.
9) The Platinum Fuel saver was sent to us with the understanding that often full mileage gains aren't seen until 2000 miles. We started seeing a difference in the first tank, and were only able to leave it in for 1235 miles, so your mileage might vary. Check out their website for more information.
10) If you talk to the Platinum Fuel saver people, they will tell you about the lingering effects of the Platinum after you stop using it. We were surprised after not seeing an increase with the K&J magnets, that these came up with a gain. Granted, it's only .5MPG, a drop in the bucket, but still after averaging each tank, we didn't see a gain of even that much.
11) We really thought we'd get better than this out of all the things added up. Oh well, until hydrogen cell swaps are commonplace, we'll take the additional 2 MPG.
12) The mentioned test points of 115,887 was when we decided to start the testing... you'll notice that the first item in the chart actually started at about 115,724 (115,938 - 213.5) and we included our recollection of miles per tank from even earlier than that. The 124,056 mileage was what was actually on the Jeep as the story was finished being written, so you can see what date that story actually got turned in, if you check the chart out.
13) One of the reasons for this chart, and the approximations we printed in the magazine was that we didn't actually run all these numbers and calculations until the last week of May. Due to the editing process, the "just under 2MPG" estimate for the Fitch fuel saver was actually on the second tank of gas in the Jeep, which really wasn't enough for a decent comparison.