steering wheel controls?

I think you can assume that. Another way to see whether navigation is installed is if the centre display has 4 buttons on the left side and 3 buttons on the right side. Non nav prii have only 2 buttons on either side.

 

There were three models in Canada in 2007.Package A or Base doesn't have the buttons (or cruise control etc). Package B has everything available in Canada except nav. It has the nav. buttons but they don't do anything (except bring up an error message on the MFD). Package C has nav as well. Look under the front seats. If there is a box under -both- seats it has nav. If there is a box only under one seat it doesn't (I can never remember which seat covers the nav. unit). The MFD buttons thing mentioned above is something I didn't know (as Pearl is Package B ).

 

No you can't make that assumption. Pre-2006 you could tell by the buttons, but in 06, Toyota had the extra buttons on some non-nav models. Look under the driver's seat to see if you have the navi DVD player. If it's not there, you have no navigation.