While playing around with different input devices (joysticks, xBox 360 controller and steering wheel with accelerator & breaks), me and my friends experienced, that there is no possibility to steplessly/smoothly drive backwards.
You can steplessly drive forward from 3-4 km/h to maximum. But if you are trying to smoothly drive backwards, all the vehicles suddenly accelerate to the maximum speed.
That sometimes is fatal in organized clan matches with motorized squads and infantry.
Please add the possibility, to smoothly drive backwards.