Although the manual is silent on the topic, I can swear that the font seats in my new PriusC warm up on cold mornings. There is no on/off switch for this to happen. Comments?
I believe this is only an option on select 3s and 4s. If you have heated seats there is a switch under your e brake where the Eco and ev buttons are.
Heated seats are only available on the 4. They are next to the parking brake next to the ECO MODE AND EV MODE Button.