I have a layout for BL2 that you can try using. It's probably not the most well made of layouts, but it was mostly just to test the AIs on the layout, so feel free to make some changes if needed.
I've a few videos myself which show some online AI overtakes
Forgive me if the quality of the video is dreadful: http://www.youtube.com/watch?v=_iVm0_xLwGQ
Check:
0:30-0:38
1:41-2:00
2:36-2:51
2:55-3:16
3:30-3:43
...There's still more replays in my folder which have a considerable amount of AI overtaking but I think this is enough for now.
Edit: A quick note, the cars in the video are running different setups, but not using intake restrictions to slow them down a lot. The differences in their lap times usually have a second or two difference as a maximum.
I got bored and decided to make one...
Just in case someone wants to use the layout, I've also attached 2 templates (16:9 only right now. I could do other ratios at some point...)
Plus the fact there are about 800-900 cars (not counting duplicates), it will take a long time to get decent sound samples from all rev ranges.
There's a lot of people blaming the poor sounds on the 256MB of RAM on the PS3. We'll see how it goes with GT7 on the PS4, but if that fails I don't know what can back it up...