Nick - There are cheap ways to simulate it though.
I've modded Warcraft3 for a year or two, and I made a very simple tank-damage system.
While it was far from advance (It only took direction, velocity, targets direction/velocity, explosive power, explosive type, armor type) it would calculate how much damage it'd do to the tank. The tank was split into 6 sections (split in the middle, and 2 ways horizontal)
Each "segment" had a different armor amount, a greater chance of deflecting the round. If the round was deemed successful at entering, that segment might do extra damage from stored munitions. I could even stop the tank from moving, if they hit the engine or the tracks.
These are what each "segment" had in it.
Armor_Type = test01 //Type of armor
Armor_Size = 20 //(how thick it was)
Armor_Deflection = 2 //(the bigger the number, the greater the chance of deflecting it, and the bigger the angle it could deflect)
Munitions = true //Due to debugging at the time, I simply had this a set number. Easily changed though
Fuel = false //Once again, debugged so it's a simple Boolean. Actual equation had amount of fuel, which the engine could use up based on 3 second intervals
Engine = false //Include both tracks and engine
But it only worked on the X and Y plane - no z. But it still worked well enough for wc3, compared to the simplistic armor in arma2.
Seems like tank hits are insta-kills anyway.