This week on Car Talk, what could make a Fiat's gas mileage increase exponentially over a few days? A holiday miracle, or might it be the same earthly reason said Fiat's mileage then decreases by the same amount? And, does it have anything to do with those guys laughing their butts off in the corner? Meanwhile, Rachel may need a miracle to keep her Camry's engine from jumping into the passenger seat, though opening her wallet might work just as well. Also, Delena's decided that six years is long enough to live with her Civic's oil leak; Darren is convinced his wife is subconsciously trying to kill his Land Rover; and, Rich wants to know if he can convert his Cavalier into a convertible. Sure, as long as he doesn't want to ever drive it again! And, Ray finally asks Tom the question that's been on everyone's minds for 25 years: What are you doing here? All this, and lots more, this week on Car Talk.