Hello,
I'm looking for an outdoor motion sensor - one that can sense when a car pulls up to a drive way, for example.
PIR sensors don't work well because of sunlight. I've seen some other ones, like the microwave/radar RCWL-0516, but also read they're pretty susceptible to false alarms.
Wanting to avoid buying more electronics that I don't end up using. Have you gotten good results with outdoor motion sensing?
If you are using the sensor in conjunction with an Arduino then it should be possible to 'filter out' any false alarms
Induction loop?
Cars (and other big chunks of metal) can be detected by an induction loop. PIR may not work for that if the heat signature of the car is not enough.
That is assuming what you want to detect is cars. If you want to detect "everything under all weather conditions" it gets harder, and multiple sensors may be needed.
PIR sensors are very suitable to detect warm things, like people and other warm-blooded lifeforms such as your neighbour's cat. Indeed work best at night, when the surroundings are cool.
Break beam sensors may work quite well, too. Place them at the entrance to your driveway and just about anything that tries to pass by will be detected - including leaves falling from a tree.