Dear AquaTune, Just a lengthy note and test results in how delighted I am with your product. Last year I put o ne of your units on my wife's 2000 Mitsubishi Montero and went from 16 mpg to 23 mpg highway miles. I was so happy with the results that I purchased a second unit for my 2003 Honda Element EX with 4-wheel drive with roof racks. I also have a trailer hitch and sometimes tow a trailer. This vehicle has an automatic transmission. The best that I have ever gotten, without the A/C on, at 65 mph, was 21 mpg. Here are the results, the best and the worst, since putting this unit on and having driven over 7,000 miles: 55 mph w/o A/C: Best - 35.5 mpg, Worst - 32.5 mpg, Average - 33 mpg 60 mph w/o A/C: Best - 33 mpg, Worst - 30 mpg, Average - 32 mpg 65 mph w/o A/C: Best - 32 mpg, Worst - 28.5 mpg, Average - 30 mpg 70 mph w/o A/C: Best - 30 mpg, Worst - 26 mpg, Average - 28.4 mpg 75 mph w/o A/C: Best - 26 mpg, Worst - 24 mpg, Average - 25 mpg With the A/C on, the results were equally impressive: 55 mph - 33 mpg 60 mph - 30 mpg, for over 600 miles! 65 mph - I went to Yosemite over the Grapevine (mountainous road), did 981 miles and averaged 28.2 mpg 70 mp h - 26 mpg 75 mph - I got 24 mpg, going to Joshua Tree, CA and back All these mileages tested out with the A/C on. These numbers are amazing!!! This is almost a 50% INCREASE OVER STOCK. I love it! The car is peppier and gets great mileage. What more could I want. Thank you so much.