two things:
1) why the fuck do you care if hes a douche? dont like him or the shit he says, heres an easy fix for you: stop talking to him.
it really is that easy.
shocking, i know.
and
2) i can clearly tell you have never driven, or enjoyed the full extent of, a subaru.
i have chosen a subaru over honda recently, and let me tell you: wow.
yeah, given the choice, i would choose subaru over honda in most cases.
and im assuming since it was his parents that its an auto.
still, its a subaru, and they are still fun to drive with slushboxes attached to them.
and if number 1 happens to be too hard for some reason, do what B said, screw his gf.
if he has no gf, then screw his mom.
there is no better come back, or good response to: "So what dude, i fucked your mom." if you actually did it.
for the rest of your lives, the conversations will go like this:
Him: "Dude, i just smoked your ass in that race!"
You: "So, i fucked your mom."
Him: "not cool."
You: "It's ok, im not trying to replace your dad, i just want us to be friends."
now, you can replace his first line with anything you want, the rest never has to change. ever.
im serious, ever.