OK, here is some info from IMDB.com.
There were a total of 309 "General Lee" cars (some of them were 1968 and 1970 model Dodges) created and mostly destroyed during the series. About 20, in various states of disrepair, still exist.
They crashed a lot of cars filming this show. Replacing the police sedans was easy - replacing the old Dodge Chargers ("General Lee") was not as they weren't made anymore. It got to the point where producers would spot a Charger on the street and would approach the owner and offer to buy it on the spot.