Interior check

Sit in the driver's seat. This seat gets the most use, and will be the most worn. It should be firm but comfortable. If it sags too much, it likely has one or more broken springs.

While sitting there take a look at all of the wood trim. Check for areas where it's coming loose, or where it's cracked, the finish is coming off, or it is missing entirely.

Note that loose trim can be easily re-glued in most cases, while cracked or missing trim can be expensive to replace.