When jacking the C5 you should use jacking "pucks", you can make them from a hokey puck and an eyelet screw or buy premade from any of the catalog folks. If you look at you owner's manual it will give you more instructios. There are places under the "rocker panels" 2 on each side, they are oval cut outs in the "frame" of the car. Those are the recommeded spots to jack. You can also jack dead center front and rear with a piece of wood between the frame and jack. those spots may be in the manual. IF you have any doubts or are unsure, please stop at a dealer of find a local C5 owner that has jacked their vehicle before and ASK where and how so as not to damage your car or YOURSELF.