The shadow and low detail is because they already said those are not 'premium' cars, so they are more like lifted straight from PS2 GT4. Their website has a complete list of cars and says which ones are premium with full rendering. But yes, annoying my MX5 isn't as well rendered because I've been using it to beat everything!
The damage simulation, I think the initial game update turned it on, iirc from level 20 on, it will affect the running of your car.
The menu, is just poor and smacks of design from a bunch of people so locked in their own project they can nolonger look at their product how the end users would look at it. Very typical problem in software design, if you ask me.
The slowness is also indefensable. Some of it to do with the menu system. They don't load things in the sequence that users would most likely advance to. It seems I need to get an SSD in the PS3 to have less frustration on waiting. But then, this is a trade mark problem, every GT has had poor loading times...
And, I STILL not seen an A2 in the used car! Polo GTI, Fiat Panda, even, not an A2!