I'm currently at the point in the Singapore mission where you fight tanks in the park. The only difference is that the abandoned enemy vehicle left for me at the beginning of this portion is a smaller armored truck instead of a tank like I have seen in all of the walkthroughs. This portion seems hard enough with a tank by watching this encounter on youtube, but with this smaller vehicle its completely impossible. Am I missing something? Im playing on normal btw.

I just beat this on Hard the other day on Xbox One. I actually was getting owned in the LAV when they double teamed me with two vehicles. (I played the game on normal too and was able to stay in the LAV the whole time and just kept moving a lot) If you stay in the LAV, mix it up with the gun and the rockets while each is reloading and keep moving. I ended up taking out the first two vehicles they attacked me with from the LAV and then bailed from the LAV and used the Explosives crate in the middle of the park. I used the SRAW and Javelin while using the small hills in the park for cover.

edit: I believe there is another abandoned LAV you can use when yours is almost gone on the ocean side of the map.

You should start with a tank in that section of the level. And after fighting through the small building, there should be another tank in the parking lot to the left just before the park. I was having a tough time too, so I restarted the checkpoint and just used the tank, sticking to the road using the cement barriers and shipping containers as cover. Even if all you can hit is the turret of tank, it's enough.

I had a similar problem, and was stuck with a light vehicle at a checkpoint, though I ended up beating it on foot with rockets and C4.