please i need help!!! has anyone here ever pass the the game forza motors sport

[carlos l]

for xbox? please only answer if if you know what game i'm talkin about and if you have already passed the game. i.m almost threw with the game, i'm in the last levels but i can never pass it cause they give me to many laps and in half way threw the race the car always slows down, it wont go any faster. so what can i do does someone know which car im sapposed to get, is there some way i can get a car that is fast and wont slow down after all them laps. please help me only if you can. thank you.