Wagons
Your train start with three wagons:
Those wagons are essential to play the game, you can't remove them or start a game without them.
Other wagons can be added to your train, after being bought at the shop in Endless or in Time Mode, after achieving a mission and connecting to the station.
Obtaining
Wagons can be bought in every station for Bolts. There you are shown three different wagons, which you can choose to buy. Bought wagons can only be upgraded after reaching the next station.
If the train has already reached the limit of how many wagons it can carry, then players will be able to replace a wagon by placing another wagon on top.
The cost depends on the Wagon, but it's 2 for the majority of the wagons (only the Light and the Slotmachine cost 1).
The cost of these wagons will increase by +1 for every additional wagon of the same type (The additional cost will add up: 2 for the first one, 3 for the second one, 4 for the third one, etc.).
Upgrading
Every wagon can be upgraded two times except for the Compass and the Light (which can only be upgraded once) and the cannon wagon (which is versus mode only).
The amount of bolts required to upgrade a wagon will usually be 2 for the second level and 3 for the third level. Some exceptions are the Crafter & the Storage (their upgrades cost 1 & 2) and the the Tansformer (its upgrades cost 2 & 2).
Upgrading a second/third/etc. wagon of the same type will add +1 for every other wagon that received that upgrade (If a Dynamite Wagon had been upgraded to level 3 already, then upgrading a second Dynamite Wagon will cost 3 & 4 instead of 2 & 3).
