Improving on 38.5mpg in 94' Prizm

[fairdinkumfrankies]

I posted this on another thread but then thought about starting a new one. I have been able to reach 42mpg under ideal conditions (flat ground, 55mph, non-Winter seasons, and no traffic to consider). I am expecting to do a 100 mile commute for a few months increasing my present trip by 5X. Most of the driving will be highway so I thought a gear change to my 5-speed might improve my 38.5mpg average. Can anyone help with a fifth gear change for a 1994 Geo Prizm? I would love to be able to reach a repeatable 45mpg average without insighting road rage in fast New England/Boston 70mph traffic. My wife said she did not want me to do extensive aero mods and my budget is very modest. I do have access to a mechanic friend and I like the lowered suspension and the belly pan.

My first post,

Neal

[Daox]

Hello Neal. Welcome to EM.

That is quite the commute you have coming up! Your best and cheapest bet is to just use the pulse and glide driving technique. Your mileage will rocket up, but it is work. You might be able to find another transmission with slightly lower gearing, but it likely won't make a large impact on fuel economy. I'm not aware of any 5th gear swaps that would work for you. Your engine uses a very similar transmission as my 03 Matrix does, and I would have died to get a new 5th gear myself.