That's what I thought too but I'm not sure. I think I've seen "Model Ses" or "Model S's". I was hoping we could get some grammar geniuses in here to clear it up.
Model S's or Model Esses. Model S' would only be used if Model S was in itself plural, it is the plural possessive. Here's a fun infographic: How To Use An Apostrophe - The Oatmeal
From the Chicago Manual of Style: So, "My wife and I love the new Tesla vehicle so much that we've ordered two Model Ss. Since our kids are grown up, though, I don't see any Model Xs in our future."
I run into that situation a lot when I post the newswires to the evdl.org. I cheat ... I tack EV onto the end, and make that plural. She bought one Tesla Model S EV. They bought two Tesla Model X EVs. {brucedp.150m.com}
This seems forced to me. You wouldn't write (or say) "They bought two Ford Mustang cars." You'd write and say: "They bought two Ford Mustangs."
Yup! I just retread my post and now I'm embarassed that I put the apostrophes in there, not sure what I was thinking!
According to Dictionary.com S's is acceptable. I was always thinking of creative ways of getting around it so I feel your pain.
As did Toyota: Prius, Prii. (Making you wonder whether these sentences are also correct: "My Prii engine is very quiet." "Everyone get into to the Prio!" "I just bought a Prium.")
D'oh! You beat me to it. I was going to say that the plural of the Model S is the Model I. (for the same reason) Person 1: I just saw a couple Model I drove by. Person 2: Yeah. The Model S in front was a pretty shade of blue.