This week on Car Talk, breaking news from the schoolyard! The Wedgie Defense Front, aka, two 8 year-olds, have invented an anti-assault device that could thwart the dreams of bullies everywhere. Then, our first half obsession with the posterior continues with Gregory, who's got a vibration and some scary noises coming from his Bonneville. Dad's suggestion? Take out his wallet and see if he feels the vibe in his cheeks. (Yes, those cheeks.) We think Gregory had better take out his wallet and hand it to his mechanic, if he doesn't want to kiss his butt cheeks goodbye. Find out what evil we think lurks in his suspension. Later, got a teenager who's about to start driving? You'll want to hear our Call of the Week, featuring Jennifer. She's trying to keep her daughter from hauling around half the high school in the back seat of their Volvo - specifically, the half with Y chromosomes. Jennifer's got an idea that's only kinda sorta life-threatening, but Tom and Ray may have a better plan, taken right out of Mama Magliozzi's playbook. Also, is 55 still the best speed for fuel efficiency? Was it ever the best speed? Finally, what's a suitable replacement for a PT Cruiser, when "PT" stands for "Piece o' Trash"? All this, a new puzzler, and lots more, this week on Car Talk.