I don't have a tuner, and honestly don't know much about them other than what their websites say. What can a guy expect to see on average in MPG increase with say an Edge or PPE tuner with the new LMM? I see a lot of them claim to have a big increase in HP and tourque. I am not really looking for that if it comes at the price of reduced MPG's. (I have a 68 Chevelle if I want to go fast). Maybe I am using the term "tuner" incorrectly to cover many different types of add on electronic performance devices but I hope you get the picture.

Tuners will help with mpg ppe would probley do the best for u people are saying they have picked up 4 miles per gallon with ppe

I have made a few trips with and without the edge installed and noticed some gain.
From Ohio to D.C. is about 400 miles, without the edge I got 18.0 and with it I was able to get 19.9. Those numbers came from the DIC. and both had at lease one or more rest stop.

I did make a 120 mile trip, and was able to get 21.3 mpg without any stops and on pretty level ground, and reading was from the DIC.

Tuning will usually make the DIC inaccurate. It's best to figure mileage by hand (trip odometer's miles/# of gallons).

Hand calculated I have seen 3-4 mpg gain depending on how I drive. Level 4 has gotten better than level three on my truck.