Since the petition has a time out period, you need to do a bit of pre-marketing to get the word out where it will do the most good.
Perhaps send a press announcement to several car magazines with enough lead time for them to get it in a future issue, and time the opening of the petition drive with the arrival of those magazine editions on the news stands.
Likewise touch base with the big message boards and high traffic car nut web sites to put in an announcement and make it a sticky with an embargo date so all this media releases the info just about the same time that the petition is started.
Press releases to any major media web outlets that you know cover a broad spectrum of racing. Find some racing legend to put in a plug through his racing contacts.
Since it is an international competition it might be worth while to shake the trees of a few people that dabble in international competitions like Larry Ellison of Oracle, his experience with the America's cup probably gives him a very good list of contacts to get this sort of word out. Maybe he knows some public relations wizard that loves racing who would help coordinate such a program so it gets off to a running start.
With that short window to gather signatures you can't wait until after the petition is started to get the word out, you need to build a core group of helpers who can dump info on all their favorite web sites and via social media like twitter and face book. Think up a good hash tag for the effort that can be used to push out the information to social media and give supportive people the "digital handle" to get the wheels rolling quickly.