In experience, I found that the 87p tune resulted in better MPG than the 87e tune.
The main thing that's going to yield better MPG is watching the weight of your right foot, no matter whether you're driving on an OEM or aftermarket tune. I simply didn't like the way the Trac felt and performed on the economy tunes. It did much better with the performance tune, and if I was conscious of my driving habits, I could get pretty good MPG on the performance tune.
I think it's a common misconception that the performance tunes will yield worse MPG. But that's only because after you upload the tune and drive it, it's so much fun that it's hard to keep your left foot from getting really heavy!:driving::banana: