According to Polyphony Digital's official site, which has since removed the info, the upcoming Gran Turismo 5 has a whopping 1,000 cars in its roster.
170 of those have fully designed interiors that also show damage, and it has 20 unique tracks with 60 layouts across them. Custom soundtrack support, and YouTube "replay output".
nabbed the info from the developer website and translated it, so we have a full glimpse of GT5's feature list. 830 of the cars are standard models, with some brought over from Gran Turismo 4. 170 of them though are premium models with full interior designs.
The other interesting revelation is the support for custom soundtracks from your PlayStation 3 hard drive and that it will support clip output to YouTube. Naturally the game also has arcade mode and a full GT mode as you'd expect from the series.
Brochures at GamesCom from Sony indicated the racer will be arriving this Quarter 4, 2009.