One hummus, two hummi

And, I have owned multiple Ford Tauri.

I had to bring my wife's Prius into the dealer for some work, so I took that opportunity to ask the sales manager if Toyota had an "official" plural form. He gave me a printed copy of a press release from Toyota ... said they get that question a lot so they ran a bunch of copies. But here's that same press release online:  http://toyotanews.pressroom.toyota.com/releases/toyota-announces-the-plural-of-prius.htm

Toyota listed all the possible variations (none of which were Priora - sorry Ron) and then let the public decide for them. Final verdict: Prii.

Edit: Just checked, and Toyota selected the name Prius from the Latin meaning "to go before" to brand their advanced hybrid technology. So if it's from the Latin, then "Prii" makes as much sense as "radii" (but I don't know for sure if the "i" ending typically applies to proper nouns). If one speaks of the Roman ruler Augustus, does one refer to his family as "Augusti" ? Probably not.

Ron Draney said
On the May 16th show, a caller who works as a waiter asked for the correct plural of hummus, and eventually decided to settle on "two plates of hummus". Along the way Grant happened to declare the Toyota Prius to have a regular English plural "Priuses".

I respectfully disagree. This came up about two or three years ago when two of my fellow Mensa members at dinner had each bought the hybrid. We decided the plural should be Priora.

Priora would be a female Prius.  Although it's not like we're talking about a Mustang.  The Prius is a gelding at best, not a male.

The plural?  I'd go with Prii. Or possibly Priii. 

I was working from analogy with tempus and corpus.