Why does my car run so much better when it's colder outside?

[walterturners 0]

I have noticed that my car runs so much better when its colder, under 40f outside. I know that this has something to do with a richer fuel mixture. How do I get this performance in the summertime? I drive a 2013 Ford Fusion and live in Texas where most of the year it's 80-100f outside.