Toyota recalls 1.3M Yaris models, which begs the question: What's the plural of Yaris?

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The 2006 and 2007 model Toyota Yaris is being recalled over a seat belt problem. In severe frontal crashes, a foam pad could reportedly ignite. The recall affects 1.3 million Yaris units (Yarises? Yarii?) worldwide, with 134,900 of those residing in the States.
Toyota is working with the National Highway Traffic Safety Administration to administer the recall. The fix evidently takes an hour at the dealership, and affected owners should begin receiving letters next week. According to Toyota officials, NHTSA has logged no reports of pad ignition in an actual consumer crash.