To be honest, the Unreal’s vehicle implementation leaves a lot to desire - by default, we have to modify the C++ bit to even have a ‘proper’ reverse gear. The default behavior is to press ‘W’ to move forward, and ‘S’ to move backward… so you keep pressing ‘S’ until it reverse the vehicle (and that is the reverse gear). So Unreal’s template vehicle is more to arcade thingy…
And one way to move forward fast is to purchase Vehicle Movement from marketplace… (you can search). I have bought one, and I think the tank movement component is working (I have not tested it yet). You still most likely end up customizing these C++ classes a lot to your requirements.