Prius C GPS - all greyed out

if you're not at a stop... those things will be disabled... regardless if you have a passenger or not. there's no option except installing an override.

you can purchase one here:
PriusChat Shop : Toyota Prius Navigation Speed Lock Override [Prius Nav Override] - $80.00

or if you search around, you can find out how to build one yourself.

 

The only way to operate navigation while in motion is to use voice button on steering wheel.

Instructions:

Press the voice button,
wait for the beep, then you say "enter zip code",
(it might respond with "cancel" the first time you say "enter zip code" but push voice button again and try 2nd time),
the car will ask "say the zip code",
wait for beep, then you say "90404" (or whatever zip code you want),
the car will ask "select line number",
wait for the beep, then you say "line 1", the car will say "line 1",
wait 5 seconds and it will ask you "say the street name",
wait for the beep, then you say "santa monica boulevard" (or whatever street you want),
wait 5 seconds and it will ask you "say the street number",
wait for the beep, then you say "8 0 1" (or whatever number you want),
wait 5 seconds and it will ask you "do you want to start street guidance",
wait for the beep, then you say "yes",
wait 5 seconds and it will say "starting street guidance"

note:
if you get the wrong zip code then push voice button again and say "enter zip code"
if you get the wrong street name then push voice button again and say "enter street name"
if you get the wrong street number then push voice button again and say "enter street number"