Grade summary

Grade Description
A exemplary racing skill
You are able to race and fight bumper to bumper with enormous discipline and consistency.
This is proven in a huge amount of dense fights on the track.

As a member of Grade A or B you are listed in the performance rating system.
B clean racer
You are considered as a gentleman and are able to actually race others for several laps. Racing accidents may happen, but it's a pleasure to drive with you.
How to improve to Grade A: Consistency and clean fighting.

As a member of Grade A or B you are listed in the performance rating system.
C rookie
You may prefer driving alone or just have bad luck often, but you're doing ok.
How to improve to Grade B: Practice to be able to hold the pace while avoiding collisions by all means. You will need some meters in range of other cars - without kissing them.
D not clean
You have been involved in quite many collisions. Probably not your fault all the time, but usually this can be improved on both sides.
Make sure you know the car and the track, and be able to drive a few laps without losing control before getting online. Be careful and treat others with respect.
W deliberate Wrecker beyond doubt
You have been identified as Wrecker. More collisions than kilometers driven, actually you probably should see if you can't find your luck in some other area than a racesim.
IF you really want to improve, find resources (will link some here) and - even more important - ask people. A majority will be glad to help out.
N Not listed (or new)
You may be unknown to the Rating system. Currently it can't tell anything about you, so you need to do some laps before you eventually receive a "real" grade. 40km are enough, that's around 10-15laps.

Grade flow overview

Note: The numbers are heavily outdated, and not that simple today. But you get the idea.