Well Eva, our LT, took her first road trip today. So I did some real world gas mileage testing.
I guess some things to note first is I put the tires at 45 PSI cold. Obviously you know what I've done mod wise. If it matters, I'm currently running Valvoline Dexos approved 5W20. And use 87 Octane; not ethanol free. Oh, there were two adults, and two 7 year old boys in the car. I'd say no more than 70 lbs in the trunk.
When we filled up for the test run, I reset the average speed, and MPG average. We drove 197.8 miles, and the MPG gauge was saying 38.5 MPG.
I must note that while the test run, I tried my hardest to get the highest possible numbers. I used cruise control at 75 MPH, (speed limit was 70) and while accelerating at all, I did not use cruise. (if you drive an auto, you know how it likes to rev up) We made one stop at a rest stop and while re entering the interstate, I did not go over 3K RPM. We never used the defrost, or AC. No heat either. Traffic never stopped, so we did no idling. When we stopped to refill, the car said average speed of 71.4 MPH
It took 5.168 gallons to fill up, giving us a real world MPG of 38.27. Not too shabby Especially for a 4 speed running 75 MPH. I'd say RPMs were 3200 average.