It's not a Fuel Tank, but in MW3 I liked trying to use the environment to kill people.
There was a map called Ice Port and in the middle was a dropship bay. The dropship bay was destructible. I'd usually make it a goal to be the first to destroy it because watching the pieces fall down was awesome (back in 1999).
Let me preface this by saying I was epic at MW3. Like, when I say epic, I mean I was Neo in the friggin' Matrix-type epic.
So anyway, I was toying with this guy, dodging all his shots, leading him towards the port. I knew he had JJ and would follow me, so for shits and giggles I jumped up into the port, enough to skirt the debris and arch over it. I shot the port about half-way up, timing it so the pieces would fall behind me on his way up.
Clean Headshot with Port Debris. Didn't even graze another piece of his armor.
Crushed his skull in with a chunk of Dropship bay.
This is a picture of me moments after:

In summary, destructibility has its place, and I wish we could have more in our game.
We don't have the resources to put forth into making everything destructible, but you damn well better believe that if we could, we would.