If you are using the sat nav with arrival time displayed that time is in 24 hour format so when you look at the clock (in 12 hour format) there is an additional mental calculation to do when working out how much longer the journey will be..
Having spoken to the dealer today, apparently it is not possible to have a 24 hour clock.
The dealer has raised a "ticket" (or whatever Toyota call it) with Toyota and suggests that anyone else that is not happy with the situations gets their dealer to do the same. If there are enough complaints then Toyota may do something about it.
I doubt they can do something, because first (of four) digit indicator is made just of two segments, if I'm not mistaken (I hope I am and the screenshot above is from production vehicle). Two segments mean there can be only one number displayed - that is 1 (or nothing displayed at all)