url-uncompressor-alist
url-uncompressor-alist is a variable defined in `url-vars.el
'.Its value is
((".z" . "x-gzip") (".gz" . "x-gzip") (".uue" . "x-uuencoded") (".hqx" . "x-hqx") (".Z" . "x-compress") (".bz2" . "x-bzip2") (".xz" . "x-xz"))
Documentation:
An alist of file extensions and appropriate content-transfer-encodings.
You can customize this variable.