Silly question: why don't you just rent EA? Weekend rental in Atlanta...should be pretty good rental rates across the board...well-stocked EA as you say... That would give you a fairly wide selection.

I rent a lot in DAL on the weekends. The rates for all sizes between Econ and Full are literally within $5/day of each other. I can't imagine ATL is all that different.

I don't know any agency can get as model-specific as it sounds like you are. Maybe Hertz? They have some very niche categories and I seem to recall the bigger stations even allow some degree of specification of model. On a weekend, you should be able to get what you want. And Hertz never upgrades anyone short of President's Circle, so if you book compact, you won't find an Impala in your stall - guaranteed.