I just dealt with LAX in December and got a great deal on a car rental through priceline. We were able to get an intermediate size car for $14 a day, it was just a bit over the shuttle prices and nice to be able to be able to stop by a store for supplies or run errands if we needed to. Priceline only uses like the top 5 rental agencies at LAX and they saved me about $50 compared to the other travel sites.
Just a thought!