One other thing I would like to address is mpg ratings for cars of the past and today.
My car, a 1991 Eagle Talon has a combine EPA rating of 18 mpg. The rating for my car is very deflated because of it being a old factory high performance turbo car.
I have looked at the factory fuel maps and ignition maps of my car and they are very conservative when it comes HP/FE efficiency. The reason they did this is to protect the engine from knock, knowing the consumer would be idiots and run regular fuel sometimes and would run the crap out of the car.
The manufacturer ran very low ignition timing numbers and very rich a/F ratios with a very low compression engine to offset the negligence of the consumer.
So the manufacturer built a very inefficient tuned engine to offset this.
So on my car I have a very inflated EPA rating of 137%. I know for fact based on another friends Talon with ECMLink you can improve from a stock EPA 18 mpg combine to 27 mpg combine just from modifying the maps in the ECU.
On my build I run stock modified pistons by me. I'm always looking for Talons/Eclipse that have not been abused to keep my piston inventory up. When I do find a grandma car engine that was driven normal the piston have the second compression ring and some times the top gummed up so bad that there had to major blow by. This proves to me that my analogy above^^^ the factory ran at a very low efficient mapped engine.
Now the newer you get the harder it will be to find low efficient cars like mine. The standards have become much more efficient since 1991.
The new STI's and EVO's etc. have increased their efficiency by running a better knock retard system compared to the ones of my cars era.
So really my % increase over factory EPA should be around 58% not 137%
Anyway some food for thought.
