Ok don't beat me up, I've done a ton of searches but not found the answer. Purchased a 2010 IV this weekend. Is here a way to display the current map version? What is the latest update, is the dealer the only option?
You might find that a better update would be Garmin or TomTom. Either, with free lifetime map updates, probably cost less than an update for the Toyota system.
I believe you go to Info-Phone->Map Data and it will give you the version. For 2010 it will be 10.1. The latest version is 2013 or 13.1. Your DVD is Gen 6. Yes the dealer will be the only option. Last price I have seen is $169.
When I bought my used 2010 Prius, it still had the 9.1 software. Being the cheapskate that I am, I went on eBay and paid $14.95 for the newest 13.1 version. To check your software version, push the phne/info button on the right side of the screen and select the map option. It displays the map version and has the option to eject the map DVD.