The best way to get involved with a rally that you really believe in or is just for fun, is to help support and organize it as a sponsor.
Contact the rally organizer and ask how you can help.
Be visible in the planning process and seek ways to get your name out there as a supporter.
Example: In a local community that hosts an annual car rally, pit stops are set up for snacks, beverages and a competitive game. Local companies are sought to sponsor each pit stop area, with a logo tent displaying their support. This is a simple, yet effective way to gain positive exposure while supporting a popular event.