Oh look at all this replies.. :)
I wouldn't want any money from it so it would be absolutely free.
It should be open source at some point. Perhaps it would be good to release tools to host private servers or code LAN in it.
I would really want to work on 200 square kilometers of the place I live in. Once that is done I could do more real world locations or atleast write a tutorial and show the procedures.
The cars would be at this level of quality.. mostly ripped from GT2. Other cars could be easily created with the help of some generic blueprints and images found on google.
The features I would want to build in would be gear, suspension, ECU, Turbo tuning.. Perhaps even a ingame car skin drawing tool. So if you want to colour your windows or mirrors or change just about everything...well perhaps that could be done somehow.
I would pretty much copy The Crew and Need for Speed World... and features from Need for Speed Underground 2.. where you can select to purchase a tower strut or small-large sway bars..stuff like that.
But first.. I'd like to try and create just 1 square kilometer in a 1999 era graphics and than write a procedure for how to do it and follow that same way of doing it for the rest of 200km 2. For all I care it can look like this xD
So yea.. I would use the cars, sounds from Gran Turismo 2.. Most probably rip textures from other racing games and use it on the transformed lidar location to subsampled mesh. I think it was never done before.. Exactly copying a location but limiting yourself to 1996-1999 graphics. And even if all this is illegal.. me no care. I would do it for the love of semi arcade racing games and online competition.