There's no reason why the 55-200 shouldn't continuously focus on any of the nikon digital bodies.
Ok basics first (I'm assuming that you're using a D90 as this is what you have listed in your profile), and I'm sure you've already double checked this, but just for the sake of completeness. Double check that the switch on the lens is set to "A", if it is already then set the switch to "M", turn the focus ring, and set the switch back to "A" again. I have the same lens and I've once had the problem where the gearing in the lens would not engage. Doing this solved the problem. Also check that the switch on the side of the camera, below the lens release button, is set to "AF" - it almost certainly is otherwise you wouldn't have autofocus whatsoever.
I don't do motorsports, but if I was going to this is how I would start.
Focus mode to AF-C. To do this first hold the AF button which is next to the top LCD display and then turn the rear dial until the top LCD display shows AF-C. I've just taken a look at my D90 and I can't see anyway of doing this through the menu.
AF Area mode to dynamic area. You can access this from the menu. Go to the "pencil" tab and then select "Autofocus". Menu A1, the first in the list, will allow you to do this. I would avoid the 3D tracking mode as I've found it is quite easily confused on the D90 when I'm shooting birds. It might work for motorsports, but I still think the dynamic area mode would be best.
Continuous Shooting. Hold the button that looks like 3 stacked photos next to the top LCD display, above the "AF" button, and twist the rear dial until you see the same 3 stacked photos in the top LCD display together with the the letter "H" next to it. This will give you the fastest continuous shooting possible on the D90.
Regarding the wide area mode for the central focus point, by all means try it. I've found it quite useful before when shooting fast moving objects, although I must admit these days I often forget to change my camera to the wide mode, and my photos don't appear to suffer as a result.
Take note though, when this camera is set to continuous focus it will allow shots to be taken regardless of whether it's obtained focus lock or not. So half press the shutter until the green dot in the bottom left corner of the viewfinder appears (it may well be flickering as the focus is constantly changing) and then shoot away.
I'm pretty sure you've done some, if not all, of the above. if you have and the 55-200 is still not continuously focusing then I'm a bit perplexed. Also be aware that the 55-200 (or at least my copy of it) is not the fastest focusing lens around.