There is no doubt that the three crew in the turret are extremely vulnerable, however there is no open air (lousy armor- ) access to the driver. I am left wondering how .50 cals can kill the driver in 1-2 passes with only the drivers slit as direct access to his position. My question is when did HTC change this modeling and was it intentional? It certainly was never part of the model before. Please understand here that you are not dealing with a new driver to this vehicle. I have thousands of kills, and hundreds of sorties since it's inclusion into the AH Inventory. I am wishing for a fix back to original damage modeling or an official announcement that it has been changed by HTC. Until such a time, I consider it as something wrong with the game.
When you, the player, jump to the gun, you, the player, become vulnerable to machine gun fire, as it should be. Therefore, if machine gun fire kills you, the player, while you man the gun, and the vehicle explodes, sending you to the tower, then things are as they should be. If you, the player, are manning the gun, what happens to the driver shouldn't matter. The only thing that should matter is what happens to the occupant of the position you are manning when the damage is done.
If you are easily killed by machine gun fire while actually in the driver's position, and "buttoned up", then there is a problem.