I usually use Hotwire. My average has been below $20/day. I generally rent full-size.. mostly Chevy Impalas. I tend to prefer them (though they may be a bit dated, byt they are quite roomy .. which is important because of long legs).

Best deals I have had, have occurred when they didn’t have the car I reserved.. Got a Mustang Convertable at $18 and a full size Yukon (Suburban sized) for about the same in SF. The Mustang was because I reserved a full size, and they didn’t have it. Yukon was because I reserved a Minivan and they didn’t have it when I came to pick it up.

I have noticed that some of the rental places try to ‘switch’ you to a lower car even though you reserved a better one…

Just ran a hotwire (sorry flu, your link doesn’t work past 10 minutes or so..). Got Economy=14.95, Compact=15.95, MidSize=15.95, Standard=18.95, FullSize=17.95, Premium=27.95. These are right off of the airport – shuttle to and from. In some cases, timing the reservation helps.. I did this one for last minute– pick up at 8:00pm today. Keep an eye on when there are events in SD or where you are going. In those cases, reserve real early or last minute. Prices rise significantly 1 to 2 weeks before event as most people place their reservations for the event at that time. Last minute gives the best chance of low price but you get the risk of not getting the car you want or not even getting a car rental.

Oh, by the way, you get better prices when renting for a full week than a few days. Multiple weeks gets you marginally better than 1 week, but not much. The only exception is when there is an event in town that occurs in the middle of the week.