I'm still not agreeing that's a valid blur. A radial blurred shot exists of three different blurs; A radial focussed blur on the front wheel, a radial focussed blur on the rear wheel, and a radial or motion blur on the background. The fact that the blur is at a 100% opacity at left side of the shot, and there's nearly no blur on the right side, makes it already invalid. Why? In GT4, the camera does not follow the car, all the cameras are at a certain place on the track. It is therefore not possible for the camera to follow the car, and in order to focus on the car, and the blurred rims, the camera MUST follow the car's EXACT track, which isn't an option in GT4...
Here's an example of the camera that follows the car:
On the side of the Carrera, a camera car drives. The camera car drives at the exact same speed in order for the camera to focus on the car's body, and not the objects that are moving, in this case both rims and the background.
Here's an example when a car passes by and the camera stands still, as in how it is in GT4:
As you can see, the background is stationary. The camera focusses on the car, takes with it the rear wheel blur, but due to the speed of the car, you see the rear of the car getting softer than the front.
However, this does not mean you cannot take a shot of a car during driving:
You see the background blurred, and the rims. But you still the front of the car softer than the rear. In order to do this, the user of the camera must follow the car through the camera's viewfinder, something which is not possible in GT4. The in-game camera in GT4 stands still, and take the photo when the car passes by, resulting in quality only where the camera focusses, which is the car, and NOT the background.