If you aren't already, then a Drive time feature durring the 5 o'clock hour needs to be in place. Sure everybody else in town is doing it, but it doesn't matter! It's money to be made.
Make it all request, throw in a five after funny, (there are plenty of services out there for this) play a cheesy on air call in game to get the listeners more involved, then go out and sell a sponsor to headline the whole thing!
You don't have to abandon the revenue from everyone else, just run the sponsors ads first and put the business in the title of the show.
Call it the "Express Auto 5 o'clock Car Tunes" or who ever you get!
It's just another easy way to make a few more bucks!