It's a bit morbid but...Well, if getting buried in the specialy made Harley casket took 4 or more plots, the Model S will certainly take many more... And around here plots are about $2,500 each, so nope, wouldn't be worth spending for 8 or more plots all together (not to mention the specialy made cement vault you would also require). A much better use is to give it to one of your relatives, or donate it to a charity to auction off.
If a Model X fits 7 adults, you can fit 7 adults in those 8 plots so it's not that much of a cost premium.