Hang in there...while it's easy to blame parents for everything (this might be in fact the case)...the kid was just trying to get a rise out of you (true, he may be spoiled, but maybe not)
He knew he wouldn't get smacked for saying it, and I don't know what the follow-up with your sister was. He probably "had" to go outside and look at your new car instead of playing Halo 3 with his friends online and he was pizzed about it.
Uncalled for, yes...I'm not "standing up" for today's generation...but, this sort of behavior has been going on for centuries.
Hopefully, he will grow out of it...it just "hit close to home" because it's your new pride and joy, and you've worked hard for it. Remember not to take too much stock in what an 11 yo says, they're practicing up for being a teenager.
