Actually, one question related to this patch.
I currently delete all motorcar, motorcycle, emergency, and so on tags via the style-file. Could I instead just remove them from the built-in tag list and thereby make the map quicker to build? (I will set new values for them, but would prefer them not to be read in at all)
I am not sure if it's really the same. At least the HighwayHook that runs before the style is applied use these tags to configure the road exceptions. So if you remove it via style the exceptions seems to be already set.
If you don't want to have it, you could better remove the tags from the built-in-tag list file but you must ensure that these tags are not referenced in one of your style file.
There is also an extra mkgmap option: --delete-tags-file=FILENAME Names a file that should contain one or more lines of the form TAG=VALUE or TAG=*. Blank lines and lines that start with # or ; are ignored. All tag/value pairs in the OSM input are compared with these patterns and those that match are deleted. This is the best way to be sure that a specific tag is not loaded from file. WanMil