sporkinum -
Welcome to EM!
I agree that a gas with more energy content could get you better MPG. But, I am also guessing that other members would suggest doing a longer test with gasohol because of the tank-to-tank variance. Maybe the ECU/PCM hadn't adjusted to it.
I got lucky with my SW2 because I could swap in an economy 5th gear from an S?1 :
http://ecomodder.com/forum/showthrea...swap-2779.html
I don't know anything about the L-Series manual trannys. If I had one I would be scouring the earth for a compatible taller 5th gear.
Hrmmmmmmm. The Chevy Cobalt XFE has a tall 5th Gear and uses the Ecotec (2.0 or 2.2, I can't remember).
IF (big if) the trannies are the same, there may be a taller 5th gear in your future :
http://ecomodder.com/forum/showthrea...lass-2040.html
Hrmmmmmmm #2. The Saturn Astra also has an Ecotec engine. It may be worth looking at it's tranny spec also :
http://ecomodder.com/forum/showthrea...tank-3803.html
CarloSW2