Have been considering a driveway sensor for some time.  (Should have grabbed the one posted several months ago...)  I think the Cartell CP-2 is one of the better ones but I forget how much solid data I had for that - it has been a while.  I did some looking around and there seem to be a couple similar ones.  I want a wired, buried one that works on magnetic fields.  I think they should be much more reliable than IR ones.  How do the Mighty Mule FM138, Cartell CP-2, and Dakota alert VS-50 compare?  Anyone have experience with any of them?  I at first thought the Dakota alert P-50 would be a lot cheaper but then figured out that is just the probe and requires a control box which the VS-50 includes.