As title says, I like wasting money on trying various things. So, let's start this off right: I actually paid for this additive, it was not a free trial so that can't be blamed as a way to skew this review. A couple weeks ago, I got the Hot Shot Secret email with a "mystery box" worth of additives. It mentioned a not-yet-released additive, along with some full-size treatments of their current offerings. All for about the cost of one full-size treatment of the available additives. Plus, it came with a free Hot Shot Secret Koozie!! That sealed the deal So anyways, the box came and I opened it to find an 8oz bottle of FR3 friction reducer, a 12oz bottle of their Gasoline Extreme fuel system cleaner (with PEA), the koozie, a small vinyl Hot Shot banner, and a 16oz bottle of "Lubricity Fuel Enhancer". So I flip it over and read, and basically sounds similar to what things like Power Service's items and things like Everyday Diesel Treatment (cl)aim to do: restore lubricity to the fuel that is stripped away as fuels get lower and lower levels of sulfur and other things. Don't take my word for it, I was a solid "C" chemistry student in both high school and college So I ran the bottle of the Gasoline Extreme during a relatively normal tankful with some city driving (maybe 25%) and heavy A/C usage. That tankful ran 375 miles on 12.89 gallons for an average of 29.1 mpg, essentially identical to my personal average with this vehicle that was 29.4mpg since purchased. When filling up after this run, I added the LFE as directed at a rate of 1oz per 10 gallons, with just a little more since I hadn't previously treated it.. 1.5oz total for what is a 16.8 gallon tank. This tankful then proceeded to follow my normal routine... back and forth to work 20.9 miles each way, with some minor city driving making up the balance. This tankful went 365 miles on 11.008 gallons, for an average of 33.2 mpg! This beats my previous best of 32.5mpg which was achieved early spring, with a nearly 100% highway tankful, so this was pretty exciting. Now I know, I know... one tankful doesn't mean jack. And I agree. So before I posted this, I wanted to run at least one more full tank to see what was going on (and more will follow to observe the trend). So, I filled up and set off towards Cincinnati with my son as we were wrapping up his summer break. I took the back highways and roads from here to Cincy, with multiple full-throttle runs to hear my son giggle, and then had various city street adventures and some stop-n-go on the interstates around Cincy thanks to construction. Spent two days there and watched the Reds beat the Angels twice, and then drove back home, covering 405 miles and still showing just over a full quarter tank. Wha....? Normally, EJ253 Subarus are rock-solid in their average usage which equates to basically 100 miles per 1/4 tank of gas, meaning as the low fuel light comes on you are nearing 400 miles traveled (usually 27-29mpg avg). But here I am north of 400 miles and still a full mark left on the gas gauge? What exactly is this LFE? Anyways... I plugged my numbers into Fuelly, and it spits out: 405 miles on 11.651 gallons of gas, for an average of 34.8mpg! On an EJ253/4EAT equipped Impreza! Needless to say, I'm pumped. I've got another tankful treated with LFE in there right now and we'll see if this trend continues. For those naysayers that don't believe, I've got 24 previous fillups logged with an average of 29.4mpg, with a low of 26.3 and a high of 32.5. Since I haven't yet done it, I am going to plug all my fuel logs into JMP 14 and do a control chart to see if these fall within statistical noise or if they are actually out of the expected range. Considering in the previous 24 fillups I had never broken 33mpg even when hypermiling (gentle, smooth acceleration and drafting semis where possible; using cruise everywhere even in town; coasting as much as possible using neutral coming to a stop sign or light; and shutting the car off at any stop longer than about 5-10 seconds) I'm going to say the results will show it above the historical standard deviation. Also, I know it wasn't due to the Gasoline Extreme; I routinely use at least one PEA based cleaner every 5k miles, and the last one was Redline SI-1 at about 4200 miles before the Hot Shot one. Anyways, that's been my experience so far, and if you're interested in trying something new, watch for when it's actually released to the market!