*NOTE*
This is in relation to this tutorial:
http://www.lfsdrift.net/index.php?topic=2.0Some people have asked me why I have to cut the layer??
Well if you cut the layer you won't have the ugly motion blur from the car.
With Layer Cut (good):

Without Layer Cut (bad):

How is this possible? when you motion blur the layer with the cut area, it will blur the background without the car, and it would look like this:

but if you blur with the car you will get that outter glow/blur (white fog as kei calls it.. haha

) and it would look like this:

In some cases you are able, and could do the second one, but most of the time you want to go for a professional look!
I hope this helped.