Yes I have been googling. I was wondering if others had had any experience with any driveway sensor devices.
posde: ty, I have seen one of those links, but not the cartell one.
tschak: My parents would like the detection to work for any vehicle, not just theirs, otherwise I really like your suggestion!
Thanks a bunch guys! I am definitely looking into buried induction sensors as IR break-beam gets mucked up by snow banks covering the sensor/receiver and PIR can trip on too many different things.