Some vehicles have incorrect animations for the gear handle.
I have only found this issue in two vehicles:
Strider
Ifrit
When driving, the gear handle animates (nice attention to detail btw!), but it shifts from Neutral, to Drive, to 3, 2 and 1st forced manual gears. This is pretty bad news for the gearbox in real life. In ArmA3, the gears on these automatic transmission vehicles are acting as if they are manual transmissions.
A vehicle you have in-game that does it correctly is the MB 4WD. If you go forwards, the shifter moves to "D", if you stop it goes to "N", if you reverse it goes to "R", same for the dashboard display lights.
Other vehicles tested:
Hunter, HEMTT, ZAMAK, Tempest, Offroad. These were all fine.