[Sohcahtoa82]

A lot of games fake the motion blur so badly. Racing games are often especially guilty.

If you're driving at 200 mph, and there's a car next to you also going 200 mph, it shouldn't be blurry.

Also, the length of the blur should not exceed the distance an object travels on your screen in 1 frame. In other words, if an object moves 30 pixels from one frame to the next, then the blurred image shouldn't be more than 30 pixels wide.