# Lateral Slip of car

I have been following this Gaming Institute tutorial and tried to make that car physics system in Blender Game Engine.

However, once I got to 1:47:30 where he starts to talk about lateral slip speed I got confused(propably because I don't know how Unity's scripting works). So it is told there that: lateral slip speed is equal to car speed dotted by wheel sideways transform. However, I don't know how to correctly do it. I mean it that I don't know if I need to take in local(multiplied by worldTransform matrix in terms of how game engines works) or global speed of car. And I also don't know if to use vector (1, 0, 0) or a global vector(in BGE it's wheel.getAxisVect((1, 0, 0)) as second input. Thanks for answers;)