Because of the altitude in Colorado we can run cars on a lower octane rating versus being at sea level but like in a couple days when I go to AZ Im gonna fill up on 87 since thats premium here in colorado but Ill being decreasing in altitude
Altitude has no effect on gasoline, your fuel injectors adapt to different environments and altitudes. When TBI and MPI was popular, yes, it did make a difference and a sensor was required for different altitudes. Not today though and carb'd engines you would have to adjust your jets for different altitudes.
Octane ratings are based upon combustion of the fuel atomization. It does burn a bit cleaner, but not a real HP gainer. Different engines require different octanes to keep the engine from detonation. The nitrogen enriched fuels act as what someone said correctly, a detergent, to clean up your intake valves and the top of your pistons. Its more of a carbon cleaner
2009 Cobalt LS XFE U74
Mods: K&N Typhoon Intake, Option Cat-Back Exhaust, Cosmo Short shifter, Maxxim Ahead 17X7's, MPx shorty antenna, FE5 Strut/shocks, Tein S Techs, Moog endlinks, Moog spring seaters, ZZP shorty header, LSJ downpipe, LNF front grille