According to the description page on Walmart, the "Prototype Batmobile" being offered was uniquely designed for the popular retailer and will have exclusive gameplay features to boot. Information regarding the driving mechanics and more in "Batman: Arkham Knight" was released in the April issue of Game Informer. The October 14th street day and information on the Harley Quinn DLC pre-order was also released through GameStop. Those who pre-order at GameStop will receive a 75th anniversary Batman poster.
Much like how the pre-orders for past Arkham games were various with retailers, it's likely we'll see more stores offer their own goodies for "Batman: Arkham Knight." Whether this will include other models of the Batmobile from the comics, cartoon, or live action movies remains to be seen. Surprisingly, a collector's edition of the game has yet to be announced, but it's still pretty early. "Batman: Arkham Knight" will arrive this year for the PS4, Xbox One, and PC.