I think the lego/ritz cracker dash idea is great. And I have been focusing more on the premium cars, because the standard ones can make me depressed. The premium ones, though, dang they look nice, and I think i read somewhere that painting any color any number of times becomes unlocked at a certain level? I can't wait for my light pink miata with bright red wheels...
I personally haven't been able to do online at all, but I suspect it's for the same reason i can't get online with my computer much either. My fiance has been having problems, too, and we're both using comcast so i'm blaming them. For now. And i'm waiting for more online updates, because I'm aware of online idiots and wish to avoid it. I like the thing that prologue did where you have to beat certain races to unlock certain online events, I think here they should do level limitations here. If you create an event, why not apply a level limitation to keep the newbs out?
Also, I agree that non abs cars shouldn't have abs (but i'm glad to have the option) and i HATE that i have to manually turn off tcs on every car individually. I wish i could set it as off by default.
I also kindof wish there were more tuning options, but as for sounds i must be the odd person. I like the sounds, but i might be used to the vacuum cleaner sounds of GT4. I chucked at the Nascar comment above.
Also yeah, why aren't there more races in single player? i had to buy a truck (or wait for a used one) and dump money in for 1 race, why not more?
And as for the zombie AI, I did the nascar series and i either finished 1st, or near last due to being spun/rammed off the track a number of times. I just figured it made nascar more realistic 
And i'm up for GRM racing.
"A dog oversteers, which is more fun than an understeering hyeena, so you want a mazda mx5 because it's rear wheel drive."