Not sure if this topic has been mentioned or not, well the official patch has been withdrawn because the patch was apparently released by error!!!!!
Here's what it said on the grandprixgames site:
Infogrames wishes to make it clear that the patch for
Grand Prix 4 labeled "patch 4.0" and released on the
website 2 September 2002 has now been withdrawn. The
patch was produced and released in error by Infogrames
without the authorisation or participation of Simergy
Limited or Geoff Crammond. Infogrames would like to
offer its sincere apologies for any inconvenience
caused. A replacement patch will be made available
shortly."