Ich hab das Spiel leider nicht, aber vielleicht hilft dieser Auszug aus diesem FAQ:

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Ranks
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Ranks are diffrent than points. After finishing a cup you are awarded with a
rank depending on your peformance on all four races. Here are the diffrent
ranks you can get.

*** ---------> The highest rank. You have finished each race with all
of your laps at "Time Trial" speed. You finished 1st on
all races. You have collected 30 or more coins on each
race.

** ----------> Excellent! You are well on your way to the *** rank! You
have good times, 1st on all races, and collected 27 or
more coins on each track

* -----------> Very Good! This should be the goal of moderently skilled
players. You have good times, 1st on all races, and
collected 25 or more coins on all races.

A -----------> Good! This should be the goal of experienced players.
You have decent times, may have finished 2nd on one race
or collected 22 or more coins

B -----------> Decent. Newcomers make this your goal. Your times arn't
your best but there good, finised 2nd on one race, and
collected 20 or more coins.

C -----------> Fair. Some problems exists. Your times need some
improvement, finised 2nd or 3rd on one or two tracks,
and colleceted 17 coins or more on each track.

D -----------> Bad. Problems exists. You tmes need improvement,
finished 1st only on one track,and collected 14 or more
coins on each track.

E -----------> Awful. You didn,t even try. Your times need major
improvement, never finished 1st on a track, never paid
attention to coins.