I love the M113 and jeep wrecks. Too bad there aren't others. On desert island, I place them for cover, and in other missions on other islands, they are good 'atmosphere enhancers'- I have one mission where a SEAL team lands on an old invasion beach, with M113s rusting in the surf. If you're clever, you can follow the rusty wrecked equipment to an ammo cache. In another mission, they are used to make a little scene- here's where a US army unit was ambushed while evacuating Everon.
What I would like is rusty, burned out wrecks for M2A2s, PBRs, T-80s, BMPs, etc. They are great eye candy and landmarks, in my opinion, and since they've already blown up and burned, they offer great cover in the desert.
I've been setting vehicles with zero health, and that's OK, I guess, but they explode and the sound kinda ruins the illusion, plus they tend to kill troops nearby.