This hoverboard doesn't have any unlockable upgrades.
Medal is the sixth limited hoverboard to get by Weekly Hunt in Subway Surfers, and was the forty-second limited hoverboard released, chronologically. It could only be unlocked by collecting 40 (Torches) during the first and second weeks of the Rio 2016 update. Like any other hoverboard, it protects your character from any obstacles for 30 seconds. When crashed, it will explode and need a few seconds to recharge before it can be used again. It has the form of a golden medal. It was released in Subway Surfers World Tour: Rio 2016