http://bugs.freedesktop.org/show_bug.cgi?id=21197
--- Comment #3 from Werner Lemberg wl@gnu.org 2009-04-15 22:15:21 PST --- It's completely irrelevant whether the unhinted numerals have the same width or not. In a TrueType font, the hinting instructions modify the advance width as needed, and this information is not available to the autohinter.
There are two possibilities: Either FreeType gets an option for the autohinting module to instruct that some glyphs (numerals and probably some others too) should have the same width, or the library which uses FreeType does this. IMHO it should be the latter.