since a search on it in these forums came up with no results, decided to post this.
Basically, carapass gives you the chance to get free games on other motion twin games.
Points earned in carapass are biddable against other peoples points for MTpasses (gives 1 phonecall worth of games in any other motion twin game) and advantages for future carapass games.
The aim is to hit all the turtles on the level in only 4 shots, each turtle when hit turns into a ball which is worth either 1, 5 or 20 points (if you hit the ball again) which you don't HAVE to hit to complete the level (rarely it can be golden which is worth 2 extra shot or black which i assume is gameover).
If all turtles are hit at the end, you'll move onto the next level on your next go (1 more turtle than before therefore higher chance for points).
Oh and you only get 1 go a day except on signup day where you get 3 goes instead (might be 5, i forgot but probably 3).
Didn't think this next line was that important but i'll say it anyway... its all in french so you'll have to guess what everything says... though its pretty self explanitory.
Link to carapass site
www.carapass.com/
Image i just made showing what the things on the subscribe screen mean
i32.tinypic.com/21mdbv7.jpg