ppm's for auto's are between 89 to 93 octain with 10% ethenal what's an auto
thats not always true, as my import prefers 96 or better! I guess if u are talking domestic, then 89 to 93 is more then acceptable. This just goes to show that every model is different. Asking such a vague question will not yield a proper reponse.
There are also many different factors: road conditions, weather, age of the auto, even the size can all play into the fuel that is needed to make your auto work properly!