This week on Car Talk, Lani developed superb nagging skills to compensate for her husband's lousy driving. Now, he's improved behind the wheel, but she's still having problems keeping quiet while riding shotgun. Can she learn how not to be a backseat driver, or does she simply have the nagging gene? Elsewhere on the marital front, Marg is wondering how to welcome her husband home from a year-long sailing adventure, with the news that his Mazda has gone on a trip of its own--down their driveway and into a tree in the backyard. Also, a home oil change goes bad for Lee in Oklahoma; Derek may be killing his clutch to keep his BMW from revving too high; and on Stump the Chumps, did Tom and Ray's sub-divine intervention help fix Father Patrick's faulty temperature gauge? All this and more, this week on Car Talk.