Cruiser is X-Rider's motorcycle, able to travel land, sea, and air. X-Rider can use Cruiser to execute the "Crusier Big Loop"/"Crusier Attack" combo to take out his opponents. In Kamen Rider Spirits, Cruiser has the ability to be operated remotely and drive itself to where X wants it to go.
X got on his Cruiser, among many other Kamen Riders and their Rider Machines, to perform the All Rider Break attack which ended the final battle with Rock Great Leader.