Computerguy, those are fantastic numbers for the V8. In some posts I have read that the auto tranny adjusts to your driving. I am featherfoot on the gas and your numbers are better then my Mazda MPV minivan.
The V6 seems to have a MPG sweetspot at 45 or so MPH. Have you found a similar MPH sweetspot in MPG using the car computer where the engine is in the most efficient cycle with the OD gear?
Your numbers are close enough to the V6 that I would rethink my plans to get a V6 since the ins costs are not too much different at my age and my commute is basically 45 MPH with a few lights .
My MPG numbers may be slightly atypical for daily commutes (the first two fill ups included daily commutes). The temperature was between 35 degrees and 60 degrees during the tour around Michigan, so I had to run the defroster briefly at the start of each day. I stopped several times on the trip to see the historical landmarks, but the car's engine was typically close to running temperature when I continued, so that probably helped the mileage a little compared to a daily commute.
The V8 auto is rated at 25 MPG on the freeway, which is just under 2,000 RPM at 70 MPH (for comparison, my truck with a 3.73 rear end is at 2,000 RPM at 70 MPH). I don't know if I have found the sweet spot yet, but the auto transmission should be in sixth gear between 45 MPH (roughly 1,350 RPM) and 55 MPH (roughly 1,500 RPM), and that range seems to produce excellent gas mileage in the V8. When you need the power of the V8 to merge onto the freeway or to quickly put a quarter mile of distance between your car and a car that has been tailgating you for the last five miles, the power is most definitely available (just make certain that you are holding onto the steering wheel tightly during the downshift to first).
My car is a late September, job 2 build, and I am thinking that Ford might have reprogrammed the car's computer for the job 2 build (good gas mileage and excellent performance when requested). A couple of tips that I learned from driving long box F-150 trucks (1979, 1994, 2004) to obtain good gas mileage:
* Drive the speed limit. If you want to be seen in the Mustang, a surprising number of people will want to pass you.
* Leave at least 300 feet or more between you and the car in front of you. If you see brake lights ahead, take your foot off the gas and let the engine slow you down rather than the brakes (this seems to work better in the Mustang, while my 2004 F-150 seems to take itself out of gear when the throttle is not pressed).
* If you have a tendency to immediately swing your right foot from the gas to the brake, you might want to reconsider your driving style.
* If you hold first gear until the engine rumbles (as I typically do), you might be hurting gas mileage.
Continuously displaying the average MPG on the dash board display is a great reminder that will help you achieve good gas mileage when you need it, while having easy access to the power of the V8 for those times when you need to have your neck snapped back into alignment.