Sub Zero

Sub Zero is the fifth episode/circuit in Angry Birds Go! It was added with the March 2014 update on the game as a preview, but the full release was released in May 2014 along with a new weekly tournament update.

Info
The episode was announced on the Angry Birds Facebook page:

Things are about to get really frosty in Angry Birds Go! We have a free new episode coming soon, so stay tuned! http://rov.io/downloadabgo

Info 2 (V.1.2.0 Update)
Break out the ice scrapers and start your engines! Angry Birds Go! v1.2.0 is now available for iOS and Android, and brings loads of new content!

This update includes:

The new Sub Zero episode! Speed your way along the snowy and icy terrain in the arctic battle of snowmobiles. There are 18 races to win.

New Info (V.1.3.0 Update)
Angry Birds Go! v1.3.0 is now available for iOS and Android! This update includes a bunch of new content, including the final two tracks in Sub-Zero and a Weekly Tournament. Let’s buckle up and go through what’s included in this update.

Features (V.1.2.0 Update)

 * Seasonal event tweaks! There is no “boss” in this episode, but rather a difficult Slalom race, where you must coordinate your way through the gates like an Olympic athlete! Also, “Fruit Splat” has been replaced with “Ice Splat”.
 * Loads of new carts! There’s only one cart available for coins (Tar Barreller L1 for 2,000 coins), several available for gems, several available by TELEPOD, and one available as a $1.99 IAP (with a bonus of coins and gems).
 * New Daily Event to earn some extra coins and gems! Compete in this event daily to increase your reward: Day 1 is 200 coins, Day 2 is 400 coins, Day 3 is 8 gems, Day 4 is 600 coins, Day 5 is 16 gems, Day 6 is 1000 coins and Day 7 is 20 gems. Also, you can connect to Facebook and double the reward! Note that the event seems to run 1AM to 1AM Eastern Time (10PM Pacific).
 * Dozens of miscellaneous tweaks, bug squashes, etc. Notable among these are a display of all opponent CC’s at the race start, squashing some impossible-to-beat challenges, and more!

New Features (V.1.3.0 Update)

 * Two new tracks in Sub-Zero.


 * Compete against your friends in the new Weekly Tournament, featuring five different race-modes / tracks.


 * Action Snapshots – These are taken throughout the race and when it’s over you can share them with your friends on Facebook.


 * As you race try to collect the Lucky Boxes for some awesome prizes.


 * Check your mailbox to see if your friends have sent you any Lucky Boxes. Then send them some in return.


 * The Daily Event rewards have been decreased - Day 1 reward is now 160 coins, Day 2 is 320 coins, Day 3 is 4 gems, Day 4 is 400 coins, Day 5 is 6 gems, Day 6 is 800 coins and Day 7 is 10 gems.


 * A bunch of bug fixes and tweaks.

Karts

 * Bomb's karts
 * 1) Tar Barreller (Level 1)
 * 2) Polar Ice Cup (Level 2)
 * 3) Cramp-on Crawler (Level 3)
 * 4) Tracked Trekker (Level 4)
 * 5) Snow Shoo (Level 6)
 * King Pig's karts
 * 1) Slushy Slider (Level 1)
 * 2) Snow Scoop (Level 2)
 * 3) Sledge Hog (Level 3)
 * 4) Strike Out (Level 4)
 * 5) Shred Sled (Level 6)
 * Chuck's karts
 * 1) Chuck Ice (Level 6)
 * 2) The Blue Cornet (Level 6)
 * Terence's karts
 * 1) Mr Plow (Level 6)
 * 2) Arctic Roller (Level 6)

Trivia

 * There are Telepods for this episode/circuit.
 * This is the first episode in an update on Angry Birds Go!
 * It is the only track not to include Champion chase.
 * After the release of the remaining levels of Sub Zero, Rovio highly decreased the amount of coins and gems of the daily event rewards.
 * A few updates later, the energy bar's indicators were replaced by cupcakes.
 * When passing through slalom posts, Corporal Pig's laugh can be heard, assuming that he's running the event.