This promotion took place on 5 October 2000, about 1 month before retail release. It seems the event used the pre-release 'Opel Challenge/Special Version'.
Above pictures taken from the following forum: https://dcemulation.org/dumpcast/viewtopic.php?t=1359
Above picture taken from the Spanish Official Dreamcast Magazine (Issue 11 / November 2000 - Page 10).
