Well, we rented a car to drive from central NJ to Cedar Point in Ohio last summer. We ended up getting a GREAT deal thru National from Newark airport. $189/week for an SUV, a Buick Rendevouz. (loaded, leather seats, 100 miles on it!) Unlimited miles.
We got this one from an email from National. This particular special was available at the airport locations, not local little offices. I would say, go to EVERY major rental company and sign up for their email specials. Our minivan had 145,000 mile son it, we were nervous taking it for a long trip......... the rental was well worth it! I would say it popped up about 4-6 weeks before the trip.