Thanks for the suggestions everyone!
Great question John; now that you mention it, I think a ~130 degree camera would work well too. My intended placement for this type of cam will be to mount it on a pole on either side of a vehicle as it passes through a service lane, breezeway, etc. similar to the example below:
We have been doing this for a while now using basic 3-9mm 2MP dome cameras with great success (one each on top, driver, and passenger side), but I feel it could be better. I was hoping to find a camera with a wider FoV, more MP, better low light quality, etc. to pick up more detail as a car passes through. Not sure if a fisheye is a step in the right direction, but figured I'd atleast try.
Something I hadn't thought about, that John pointed out, is that too wide a FoV means shorter effective coverage area; which is probably at least one of he reasons why the 5MP UDP still has an overall "fuzzy" image when attempting to use it in such a manner. I just recently got a Hikvision DS-2CD6362F-IV in hand as well, which isn't bad looking preliminarily speaking, but won't know for sure until I get it installed in a proper test environment.
Again, I apprecaite the suggestions and will continue to take a deeper look into each one.
Thanks!