On the web site, cars are listed by class. I care about models, not classes. I see the example car, google it to determine if I like it, choose it, and then... show up at the place and find I'm given some horrid substitute that I don't know much about. Oh, it's a "full size sedan" and all such cars are interchangable? No, really, they are not.
It is super-important that I know exactly what I will end up driving. I'd like to know the options, trim level, and ideally even the color.
Best would probably be that I check a box for every acceptable model, with a minor discount if I check lots of boxes. (being non-picky makes my order easy to fulfill) This way I can exclude models that I hate, and I have plenty of time to research all the different choices in advance.