Everyone knows you can use the "Hatch Open/Close" keys (default Arrow Up/Down) to close the armor slats on the Hanomag's view ports. The problem is that people can still fire directly through it and hit the driver with small arms fire, regardless if it's open or closed.
The Dorchester also has this function, but it seems to actually protect the driver when the hatches are down. This leads me to believe it is possible in the engine and it was just an oversight during the testing.
Hanomags are already death traps because of all the Tanks, AT Guns and AT Rifles all over the place. Being able to snipe the drivers out regardless of whether or not the armored hatches are closed is just overkill.
Also, a slightly related question: Are the Hanomag's MG's traverse correct? The rear one seems unnecessarily limited in it's traverse especially... If it's historically accurate to the vehicle, I don't mind, but I really can't figure out why the Germans would make the MG's field of fire so limited. I can understand the armor on the forward MG restricts movement, but the rear one is just on a pintle mount...