***This achievement is unobtainable as of April 13, 2012 due to server closures.***
This is best done on Drag Strips. Pretty easy if you play just a few races with friends or boosting party's you should get it first or second try most likely. Just have all 8 players stay in the match and don't quit and keep racing all the races until you all get 10,000 points each then finish the rest of the races off, when you get at the end of the match list and finished them all it should pop the achievement. You need all 8 to be real players not AI members. Must be ranked.