[Update] The Official PlayStation YouTube channel has released the trailer and details for the Batman Arlham Knight September Update, which can be viewed below: 

The newest series of add-ons for Batman™: Arkham Knight – 2008 Tumbler Batmobile Pack and Original Arkham Batman Skin, are available beginning today for fans who have purchased the Batman: Arkham Knight Season Pass and are connected to the Internet.

The 2008 Tumbler Pack places you in the cockpit of the iconic Batmobile from the 2008 film ‘The Dark Knight’ as you navigate two movie-inspired tracks in the Tumbler. Challenge and compete with your friends for the fastest time or wreak havoc on the destructible streets of Gotham City upon full eradication of all drones. Additionally, today’s free-to-download Original Arkham Batman Skin lets you invoke fear into the eyes of your foes wearing the suit that started it all, the original Arkham Asylum Batman Costume.

Additional DLC coming September 29th:

• Crime Fighter Challenge Pack #2: Grab this Crime Fighter Challenge Pack and receive various challenge maps for Batman, Nightwing, Robin, Catwoman and the Batmobile. This expansive challenge pack allows focused training in Freeflow Combat and Invisible Predator stealth incursion.
• GCPD Lockdown: Set after the events of Arkham Knight, play as Nightwing to stop the Penguin from breaking out of the Gotham City Police Department in this thrilling story pack.

Batman Arkham Videos has released some new gameplay of  Batman: Arkham Knight featuring the "2008 Tumbler Batmobile Pack" and "Original Arkham Batman Skin" as well as the Batman Begins \ The Dark Knight Race Track.

After clearing the streets of the drones tanks, the Tumbler can be used in free roam, no Battle Mode is available for this Batmobile, so players can't use the Tumbler in tank battles missions or during the story.

The Tumbler DLC for Batman Arkham Knight will be available later today

The Batman Arkham Asylum skin is a 13MB download, while the new Tumbler Batmobile is 590MB.

Recently Rocksteady has made available the Big Head Mode for Batman Arkham Knight, which can be viewed in the video below, with instructions on how to activate it further down.

Big Head Mode Cheat for Batman Arkham Knight

Big Head Mode can be activated in Batman Arkham Knight by holding down LT and RT on Xbox One or L2 and R2 on PlayStation 4, and moving the right analog stick clockwise and the left analog stick counterclockwise at the same time, until the cheat is activated. The Big Head Mode Every enlarges the head, hands and feet of every character in the game. To remove the Big Head Mode just repeat the cheat or restart the game.

Game Director Sefton Hill, addressed a comment he made in the WB Forums, about other characters possibly free-roaming around Gotham.

“We wanted to clarify that this is not a feature that we are currently working on and we have no plans to work on this,” he said.

Hill added that they spent over three years filling Gotham with missions for Batman:

When we set out to create the ultimate Batman experience in Arkham Knight, a big part of that was making an environment that feels natural and fun for the caped crusader to traverse and explore. Everything in the city is tailored to Batman – from the height of the buildings, to the width of the streets, to the lighting on the rooftops and everything in between. Other characters can’t grapple-and-glide or drive the Batmobile like Batman, so for them to feel authentic they would need to navigate in their own unique ways. And when that’s done, even Gotham itself would need to be modified to get the best out of this new gameplay. Without a prohibitive amount of work, it just wouldn’t be fun or feel authentic to what makes these incredible characters unique.

Batman Arkham Knight is available for the PlayStation 4, Xbox One and PC. We will bring you any new information on Arkham Knight as soon as it becomes available.