Answer:
Arnett - red car
Bradley - gray car
Church - yellow car
Dawson - silver car
Explanation:
1st clue - we know that Bradley and Church can't have the silver car.
2nd clue - we know that Dawson can't have the red or gray car.
3rd clue - we know that Dawson and Arnett can't have the yellow car.
Based on the 2nd and 3rd clue, we know Dawson has the silver car because he can't have the red, gray, or yellow car.
4th clue - we know Bradley can't have the red or yellow car.
That leaves us with the gray car for Bradley because he had lunch with the owner of the silver car (which i consider also a bright color but i don't know if that counts).
so far:
dawson - silver car
bradley - gray car
and we know arnett can't have the yellow car because the owner of hte yellow car thinks he got a better car with his car then dawson and arnett, which leaves us with the red car for arnett.
dawson - silver car
bradley - gray car
arnett - red car
by process of elimination, that means church has the yellow car.
arnett - red car
bradley - gray car
church - yellow car
dawson - silver car