I like the sealed envelope license idea. 2 way radio's are a must with a SET channel for all drivers. A longer 300+mile or so run would be fun, maybe start it Saturday night and end it Sunday night or something, that'd be fun. Also, maybe just have check points (don't time it....officially) and just hand people a map, make them figure it out? That'd make it fun if 10 cars take one route, 10 take another, 10 take another etc....