I would say to sit in the dark with your shotgun on your lap... but some may find that politically incorrect.
How about a nice motion detecting alarm? And a good heavy car cover. When it is lifted, it will make the alarm sound and scare the crap out of them, and wake you up.
If you attach the emblem too well, they will damage the car getting it off. Chances are that they will eventually try for the other emblems too. A noise maker is the best defence I can think of. It may be disruptive for a short while when the cat sets it off and so on but eventually the crooks will learn that it's there and hopefully decide that there is too great a chance of getting caught to risk it.
It's prolly kids in the neighborhood just bored. Funny that it's happening in the burbs though. If it were ME. I'd wait them out and sic the dog on them.... oh... I forgot... I don't HAVE a dog! LOL
Kate