This applies only *after* the "time-3" patch in this topic: http://forum.simutrans.com/index.php?topic=6629.new#new
This displays the tiles/month equivalent for 100 km/h in the goods list window (underneath the speedbonus information).
I tried to do it in a "clean" manner, so there are some random cleanups in the code (using symbolic constants instead of raw numbers) as well. This turned out to be easier than I expected.
I haven't sat down and timed a convoy yet (50 km/h convoy over long straight 50km/h road, perhaps). Other than that it appears to work -- any computational errors should be fixable with the same structure.
EDIT: For James Petts, the adaptation of this to experimental is on the experimental-speed-trans branch on github.
HEY! SIMUTRANS DEVELOPERS!
Like with the "time-3" patch in the other thread, this has apparently been ignored for two months. Could someone please take a look.
Updated patch.
Not me before June.
Updated patch, applies against head plus "time-5" patch.
EDIT: updated to apply against head plus "time-6" patch, thanks to discovering that I lost bits of the patch in time-5 (time-6 seems good).