These are files compressed with Zlib but I can't see to decompress them into a readable format.
I ran a Python script which tells me that the header is 9 Bytes. I have
02 01 63 62 64 2e 04 00 00 78
It's a compressed text file. There is actually a tool available with the games to decompress/export these files as text (.xml extension) already but it involes loading several hundred megabytes of data, even for a for < 1 KB file. I think that QuickBMS may be more efficient.
example.dbc.txt [242 Bytes]
Downloaded 6 times
The true file extension is .dbc but the forums wouldn't allow me to attach it.
There are more .dbc examples here: http://uploaded.net/file/2w99fykv