Format only long lines
From Vim Tips Wiki
You want to format/wrap long lines, but not touch shorter lines.
Example: For each line longer than 80 chars, run that line thru the par text formatter.
:g/.\{80,\}/ .!par w70
This need arises when you cut/paste a programming snippet from your web browser into Vim, and you want to leave the indented code alone, but format the long explanation.
See VimTip584, on the capabilities of par.
[edit] Comments
How is this better than gq with a line width of 80?
