The only thing I found out is that the proprietary navigation systems of the manufacturers all use the same map data, mostly from TeleAtlas. You find map CDs from the manufacturers but can also finf TeleAtlas CDs suitable for many manufacturers.

What I also found out (at least I thought so) is that some of the TeleAtlas CDs use the GDF or Shapefile format and should therefore be useable for this project.

see:
http://exchange.manifold.net/manifold/manuals/5_userman/mfd50Import_Drawing__GDF.htm

or:
http://www.na.teleatlas.com/products/formats.html

or:
http://www.imit.uni-hildesheim.de/Firmenbesuche_SS01/bericht_teleatlas.asp

or:
http://www.megatel.de/down_rtf/teleatlas_geodaten030724.pdf

Has anybody a map CD from TeleAtlas or one of the car manufacturers to compare it with the GDF specification?

It could also be a way to use the source code of the roadmap project ( see http://empeg.comms.net/php/showflat.php?Cat=&Board=hackers_prog&Number=187407&page=&view=&sb=&o=&vc=1 ) and adopt it to the GDF format.

Juergen