Steering on mobile sets the steer value to -1, 0, 1 and throttle to -1, 0 or 1. This is a really gross experience on mobile! The values should be set (with a small deadzone) to any value between 0-1, depending on where the joystick is held.
I wrote a boat earlier that would handle even better on mobile than on desktop, but for some reason the mobile core controls are defeating the purpose of having a stick versus a keyboard!
The main issue is that Steer and Throttle properties for vehicles only take the integer values 0, -1 and 1. You can change the Torque dynamically to create the desired effect for the Throttle property but as far as I know there is no way to do this for Steer.
These properties should really be floats but changing this now might break replication or serialization. I’m not sure but I think we probably have to add new properties instead.