Two retailers today confirmed the Batman: Arkham Knight Batmobile Edition as cancelled.
Warner Bros. has released a statement to Kotaku with similar information in the GAME retailer's email. It states the reason being due to the quality of the product, not specifying on what (likely the Batmobile).
"We regret to inform you that we are not able to release the Batmobile Collector’s Edition of Batman: Arkham Knight due to unforeseen circumstances that greatly compromised the quality of this extremely limited run of product. We are deeply apologetic for this unfortunate outcome. If you did pre-order the Batmobile Collector’s Edition, please go to the retail location where you pre-ordered the product and you will receive a full refund of your deposit or it can be rolled over to another Batman: Arkham Knight edition or another product of your choice. We will be providing everyone who purchases Batman: Arkham Knight with the New 52 skin pack, including Batman, Robin and Nightwing, free of charge."