The official plural of Toyota's "Prius" is "Prii"

Have you ever wondered how the plural of a new word is decided? For "Prius", Toyota decided to have an online vote to make that decision for them. After a general vote of the public in 2011, Toyota decided that the official pluralization of the word “Prius” is “Prii”. So if you see a bunch of Prii driving down the road at the same time, you’ll know exactly what to call them.