permissions/access to group specific information

I have 20 or more users that may or may not be part of the same dealer. I am trying to make sure salesman for particular dealers only see that dealers quotes. 
in my dealers table I have users,  and company name. 
I am unsure of how to go to the participant role and make a rule that says if a quote shows company name x , then allow users 1, 2, and 3 to see those quotes but nobody else. 
I thought about making different rolls and just naming them the dealers name and creating permission levels that says if Dealer name shows "x" then they can see it. But there is an easier way to do this than I know of right now im sure.