This week on Car Talk, does a dorsal fin make a car less aerodynamic? That's Dan's question, after he decided his Tercel was lacking that important fishy feature. So, he sculpted one for the hood. Is such a problem even possible for a Tercel? Elsewhere, Mary's been driving her Mustang around with a trunk full of compost. Her husband says it's time to clean it out, but Mary thinks the ballast is worth a few mold spores. Also, Vanessa's Sunbird's making a classic rattle, Eddie's F-150 won't start, Megan's looking to get a new car and a new guy; and Stephan's about to learn there's a fine line between Genius and Wacko--and me may have just crossed it. All this and lots more, this week on Car Talk.