I would like to be able to detect whether my car or my wife's car is parked in our garage. I know there are lots of ways to detect the presense or absense of a car (photo eye, proximity, etc.), but I want to be able to detect that the two cars are mine.
What would be the lowest cost hardware options to do this? I suppose I could do it with GPS, but that is fairly pricey for such a simple task. I looked briefly at RFID which has the advantage of one end (the auto end) being passive. I could do use a low cost wireless transceiver, but that would mean I would need an Arduino and the transceiver in each car, plus one in the garage that could then connect back to my home network in some way. Could use Bluetooth, but that hardware costs a bit more also.
What are your thoughts?
Thanks in advance!
Brad
What are your thoughts?
Buy a Foscam web cam and put it in your garage so you can just take a look and see. For $50-100 the foscams have a lot of interesting features.
Is it likely that someone else's car would be parked in your garage?
As for the webcam idea, I can definitely do that if I want to take a look. But I'm talking about a simple boolean detection of "is car someID in garage" that I could then use to trigger events and actions on home automation devices. Would not want to try to do vision recognition... 
And while not likely that someone else s car is in my garage, it does happen from time to time. Like when relatives are visiting, etc. Plus, we have a keypad to the garage door opener. We've been known to give out that code so someone could drop a package by the house. Would not want that to trigger unlocking the back door, turning on lights, etc.
diverbw:
I looked briefly at RFID which has the advantage of one end (the auto end) being passive. I could do use a low cost wireless transceiver, but that would mean I would need an Arduino and the transceiver in each car, plus one in the garage that could then connect back to my home network in some way.
... and not just passive tags on each car, and one Arduino/detector connected to your home?