After about 4,500 miles of testing, I have come to a conclusion about single shots.
They do improve MPG
- by about 1%.
I changed out my 218,000 mile splits for new singles from a top injector outfit. I got six different tunes as well Two of those were better than the rest.
With my old splits, I got 26.9 MPG
summer mileage on my normal loops (35% urban, 35% two-lane road, 30% Interstate - all driven at posted limit or close as I can get). With the single-shots I averaged 27.3 with the two best tunes. I obviously have not tried them in winter yet.
I have not monkeyed with my aero package since starting the injector test.
Not a drop of additive of any sort has gone into the tank since starting the injector test.
Oddly enough a tune approximating a commercial performance tune did quite well once I changed my shift points. Normally I shift at 1200-1300 RPM. For his fangs-out MPG
tune, this worked well, but for the performance tune it made my truck smoke like a steam locomotive. By shifting at 1800 RPM (high RPM for me) the turbo perked up and the smoke cleared. When all was said and done the two tunes gave with 0.02 MPG
of each other. My margin of error is usually about 0.3 MPG
Make of it what you will.