Extra large can of gasoline.
The item id for Gas Large in unturned is 1440. You can use this ID with the commands below to spawn the item, give it to a player or buy it on a modded economy server.
Useable: Fuel
Size_X: 3
Size_Y: 3
Size_Z: 0.5
Fuel: 2500
Blueprints: 1
Blueprint_0_Type: Tool
Blueprint_0_Supplies: 1
Blueprint_0_Supply_0_ID: 28
Blueprint_0_Supply_0_Amount: 5
Blueprint_0_Tool: 76
Blueprint_0_Level: 2
Blueprint_0_Skill: Craft
Blueprint_0_Build: 27