Why do so many people put an S in front of 60, 70D, 85 and 85D? Isn't it kind of pointless? Why say S70D? There is no P70D. So isn't 70D distinguishable enough? 60 isn't distinguishable enough, 85 etc...? I kind of understand for newbies to the Tesla world but for folks who've been around awhile to say it kind of makes me scratch my head.