This week on Car Talk, should Mary let her 17-year-old son accept his girlfriend's mother's offer to give him her vintage Dodge Dart? Is Mom offering the car as a dowry substitute? Elsewhere, Cathy may have to resort to riding around wearing a football helmet to get her husband to get rid of his old Corolla; Carl earns Bad Idea of the Week honors for wanting to mount a snow plow to the front of his mini-van; and Chana's Dad's advice about warming up her car may be a subtle way of telling her he thinks she's a stinko driver. Also, how on earth did a parking valet start Kenneth's Subaru with the key from Kenneth's Caravan? All this and more, this week on Car Talk.