QUOTE(http://www.gamefaqs.com/console/wii/file/942008/52407) said:
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Star Ranks
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You will be ranked based on your performance within the Grand Prix, up to
three stars. You need to one star many of the cups in order to get all the
unlockables, so it is important to know how to get them. To three stars,
you have to win ALL four races and get 60 points, and get very good times
on all the laps. That is it, help yourself to items and what not. Just try
not to obviously fall off the track or hit into walls, as it will slow your
time down.
Note that you do not _need_ 60 points to get ONE star. You can drop a few
points, but as long as you get a decent time and come first it is possible to
get it. Thanks Amphetamine!
To get stars next to your name online, then complete _every_ cup with stars.
All cups with one star gets you one star, two gets two, and three for three.
Note if you have three for all except one, then you will not have three
stars until you get that cup up to scratch.