i've got it!
this website should help you out: http://www37.atwiki.jp/wangan-midnight/pages/20.html
basically with the card system, its power up everything from more power, overboost, cooling mods, handling mods etc etc, depending on the rank you get in the mission depends what type of cards you will get.
this page will explain what each card does
http://www37.atwiki.jp/wangan-midnight/pages/12.html
just use google language thats what i did lol