Can emacs pick proper coding system intelligently?

[Scott Heftler <lovecraftian@mac.com>]

Yesterday I have a problem.  I would read a RMAIL-mode file saved via
`gnus-summary-save-in-rmail' and the ellipses would be escape-quoted
and display as \205.

I was told that I needed to find the file using windows-1252 as my
coding system.  Now the windows-1252 ellipses display nicely when I
run `universal-coding-system-argument' (C-x RET c windows-1252) before
finding the file.

You'd think that, when emacs encounters these \205s, it would KNOW to
pick windows-1252.  But it doesn't.  I put these in my init file to 
help it along:

(prefer-coding-system 'windows-1252)
(prefer-coding-system 'utf-8)

This makes sure utf-8 is top pick, and windows-1252 is second.  This 
did nothing.

Is there no way to AUTOMATE emacs' pick of coding system?  I thought
it chose coding systems intelligently, based on file contents?  Do I
really have to open a file, see escape-quoted characters, guess what
coding system I should use, close the file, and then reopen it using
`C-x RET c' in a trial-and-error fashion?

-- Scott