Long ago, I made a favicon.ico custom icon for the Milwaukee Without A Car website, but I don't remember how.... I think I created a .bmp image and simply renamed it...
So I found a new SVG of the same graphic, but I'm not using it - instead I'll stick with the old favicon until inkscape can export to .ico files.
Another example showing how SVGs and their tools have great promise, but aren't quite there yet.