Nope. If it is still images, you get bokeh, if it is panning images, you still need fast shutter speed to render the background blur and subject sharp
Nope. The slower the shutter speed, the more blur you will get for the background for panning shots.
The longer the shutter is open, the longer the image sensor is exposed while the camera follows the moving car. If the camera follows the car's movement at an appropriate speed (depends on the car's speed), then the car will appear sharp in the image captured as the car's image remains largely steady within the camera's image sensor during the whole duration of the opened shutter.
At the same time, during the duration in which the shutter is open, the background (which is stationery) will move across the image sensor as the camera follows the car's movement. So the slower the shutter speed, the more time the background is allowed to streak across the image sensor and therefore the more blur the background will appear in the captured image.
Try using slow shutter speed of 1/10 or slower and pan your camera, you are likely to get movement blur image. But if you try 1/1000 or faster and pan your camera, you're likely to get everything from foreground to background all without movement-related kind of blur. (Bokeh and DOF is a separate issue altogether here).
The key to panning shots to have blur background is to have a slow enough shutter speed (not fast shutter speed as you said) relative to the panning speed (of movement of camera following the moving car/object) so that the background actually streak across the image sensor during the time when the shutter is open.
Therefore the appropriate shutter speed for panning is usually around 1/60 - 1/250, depending on how far, how fast and how large the moving subject is.
This can be seen in that, in stark contrast to panning shots, a fast enough shutter speed is required to avoid movement related kind of blur captured in the final picture.
This is exposure 101.
Anywhere here's a thread containing some panning shots of F1 cars during the Grand Prix at Sepang last weekend. Shutter speeds used were 1/125 or 1/160 or 1/250. The slower the shutter speed used, the more blur the background will be but there is an increasingly higher risk that the car is not sharp as you need to maintain the car's image steady on your camera's image sensor for a longer duration (slower shutter speed = longer opened shutter duration).
http://www.clubsnap.com/forums/showthread.php?t=362288