tell me how you think his going away party would be an ideal time to steal his wheels...
all of his friends will be there. everyone will be trashed. he's going away soon so it's not like he'll think twice about absolutely beating the shit out of you. or even better yet, if you happen to do it without anyone coming outside while you're doing it, i'm sure you're the first person he'll think of, and he'll just come and fuck your car up even worse.
i would just wait until like an hour or two after the party starts, and then call the cops and say you're a neighbor and you see a bunch of kids doing lines and smoking weed.