GRAN TURISMO 5 HELP PLEASE?

why are b-spec drivers so stupid and not do what you tell them to do... if you tell them to overtake, they dont, if you tell them to go quicker they just crash and then wait for everyone else to drive past... the only way to win b spec is unless your car is 100 times better than everyone elses which in about 70% of races just isnt possible... any help ?? xx