How much loot do I get back from the new loot cart?
After getting attacked, the loot cart will randomly appear somewhere in your base, and will contain 20% of the loot you lost in the raid. This will not affect the amount of loot that the attacker gets, you simply will get some of your loot back as a sort of consolation prize. If you are attacked multiple times without you having collected your loot cart, the amount of loot you get in the loot cart will update to represent 20% of the loot you lost in the raid you lost the most loot in, but only one loot cart will appear at a time, so you should collect them whenever you can.
Note, you cannot collect a loot cart if your storages are full.