I'm on my second bottle of the new PI. I do about 3,000 miles a month in the truck. Gas milage is about 22.5-24 average most tanks. I can't really say I have personally seen a big difference, but I was a faithful old PI user.
I have a few friends that are using it, that never use additives. One has a GMC 1500 and he pulls a 6,000 lb trailer. He said his fuel economy went up significantly (no exact figures) but he said he had the same mileage on the tank pulling the trailer than he did running empty. I wish he would have given me the exact numbers.
I really think it doesn't matter what type of fuel you use, there are not enough additives in the fuel to do a good "cleaning" and a period maintence like PI or Techron is a great idea, especially with the price of fuel now a days.
I did notice in the auto parts store that Techron is about $10 something a bottle for the 20 gal treat. The retail on the amsoil is less than that, which is a good thing.