From my experience at King's Dominion and Michigan's Adventure, if you show the voucher to the parking attendant they should scan it and let you in.
Total Coasters: 134
Top 10 Steel: Maverick, Skyrush, Intimidator 305, Banshee, Millennium Force, Raptor, Superman: The Ride (SFNE), Top Thrill Dragster, Big Bad Wolf, Volcano
Top 10 Wood: The Beast, El Toro, Phoenix (Knoebels), Boulder Dash, Thunderbolt (KW), Mystic Timbers, Comet (Hershey), Hercules, Shivering Timbers, Jack Rabbit (KW)
Top 5 Hybrid: Twisted Timbers, Goliath (SFGAm), Wicked Cyclone, Great White, Gemini