I have not or ever done glass engraving and don't think I could,I just do not like how it looks and it may hurt resale.......where-as tracking systems are hidden with NO damage to the car.Also tracking devices are transeferable from one car/toy to another(all bikes,cars,snowmobiles or boats)!
I ordered one of these:
http://apstracking.com/qa.html
And if it moves I get an email,phone call or text message.The basic system is supposedly real easy to install too.
I do believe,for an extra fee, that you can track/check it on the internet.....I have seen a demo on it and was sooo impressed.
Stacy