it happened to brian coglin. last christmas eve, coughlan went to run errands in his prius.he turned on the car. >> there was a loud rumbling noise in the car. >> reporter: it sounded more like this. >> that's how you know it got stolen. >> reporter: across the country, catalytic converter thefts have shot up. the reason there are precious metals inside, which have become more valuable, especially with tougher emission standards rhodium, in particular, is up 82 800% in march to nearly $20,000 an ounce >> in this district alone we had over 32 catalytic converter thefts. >> that's how they do it. >> reporter: mechanic walt morehead says converters for some car models are on back order and replacing them is expensive. >> what you have to replace is everything, here all the way back you can't just get this piece. >> reporter: what's it going to cost this customer >> this one is going to be close to $3,000. >> it also happens to the same person repeatedly. so i have been a little concerned about that. >> reporter: some car owners are buying special plates to try to prevent theft.