I like some of the ideas that the GT5 dealership put in (namely, the constantly rotating schedule), but overall I think GT4 did everything much better. But a Standard Car dealership? No. It is basically that already, and it annoys me to no end. In fact, I would go the opposite way, and integrate the older Premium models in with the Standards like they should have been in the first place.
I do think there are some easy things that could improve it, though. For starters, I would split it up similar to how it was in GT4, with three used dealerships: 1980s and Previous cars. 1990s cars. 2000s cars. 32 cars at any time in each list. That would greatly help out the problem with too little cars being available, but would leave the benefits of the "random" lot in.
There are also some pretty stupid problems with the car prices (the overwhelming majority of them are at least twice as expensive as they should be), mileage (the majority of the cars are far too light on mileage, which makes the need to do an engine rebuild on all of them even dumber), rarity (one-offs and famous race cars show up in the lot far too often), as well as the random element (which clearly has an extremely limited list to choose from, which results in the same cars cars painted in the same color combination popping up over and over again).
