It is a fairly uncommon object, and when shot or ran over with a vehicle, it will explode with a powerful force, creating a black mark on the ground where it blew up, similar to the fuel dispensers found at gas stations. They are most commonly produced by Pharte Gas. The explosion is much more powerful than a Grenade, which could destroy vehicles rapidly, as well as killing nearby people, including the protagonist if he got too close to the blast. Using appropriate mods in GTA IV, it is possible to spawn a Barbeque Tank anywhere, and can be blown up like regular tanks, as seen in this video.