git: Retrieve a single file from a repository

What is the most efficient mechanism (in respect to data transferred and disk space used) to get the contents of a single file from a remote git repository?

So far I’ve managed to come up with:

git clone --no-checkout --depth 1 git@github.com:foo/bar.git && cd bar && git show HEAD:path/to/file.txt

This still seems overkill.

What about getting multiple files from the repo?

git: Retrieve a single file from a repository