The most pristine and frequently used "Baby" only has 15,000 miles on it.
The show single-handedly made this particular car model wildly popular. In fact, it's become difficult to find the car, since it's in such high demand.
The wrecked Impalas from the show definitely stick around. In fact, you can see various parts and pieces lying around in specific scenes. Think junkyards.
Fans love to make replicas of the car. They even used a fan's restored car to film that spinoff pilot episode for Bloodlines in season 10.