Questions about sponsorship.

Does anybody racing have sponsors for their cars?I was approached yesterday by my engine builders(brothers)about sponsoring me.We really didn,t go into detail much cause I was kinda in a hurry.What I want to know is,what have some of your sponsors done for you?Wether it be your engine,car parts,paint,travel expenses.Was there any contracts involved?Any help would be appreaciated as I,m new to this and looking forward to any new free mods for my car.Thanks.:burnout: