I'm price and car conscious, meaning: 1) I usually want a specific car (high capacity, off-road capable, etc.), and 2) I hate how expensive the big boys are. Flightcar was also a great concept for my wife and me, as we spend a good amount of time in another state where Flightcar had operations, so we could leave a car there and use it when we were in town.
When I can, I rent with Sixt, which is typically way cheaper (though their customer service is also horrible and still has the same issues being a car rental agency). It's not that the rental agencies are always that expensive, but when the taxes and fees get tacked on, it's absurd and it's not something I want to support when I don't have to. (Energy Surcharge, Customer Facility Charge, Vehicle License Fee, Concession Recovery Fee.) It's like a restaurant charging you for a burger, then having fees for the condiments that come on it, the booth you're sitting in, and for having the lights on while you're there. Recently in Costa Rica, we rented a car for $10/day, but with fees, it came to about $100/day. But I digress...
Since I always look for deals, it means I'm switching between rental agencies and not sticking with one, so I've never seen the point in setting up rewards account. But your comment makes things sounds way too easy, so maybe I'll take the time and give it a shot. Thanks for the tip!