just buy it if you want it. the value isn't there though so definitely not a good investment. I got the P instead of the S because I knew when I had a V6 camaro for years I was always PO'd that I didnt choose the V8. well, that and at that time (2012) the P included a lot of the now "options" for free. that is no longer the case. You'd literally be paying $30k more for a .75 increase on 0-60 time and that is it. (post 60mph the P and non P are essentially the same). it's just not worth it unless $30k is pocket change to you.
I do agree that it is not a good investment...but it's also true that probably NO $90,000+ Model S is a "good" investment.
The price difference between the 85D and P85D is $20,000, not $30,000. With 7% tax, its about $21,400.
The speed difference is 1.3 seconds, not .75 (4.4 vs. 3.1 sec). Nonetheless, that "small difference" in 0-60 is really not a small thing...its the difference between "fast car" and "super car" territory. For $20,000, its a bargain. Look at the cost of cars with similar performance...all much more expensive, with much greater total cost of ownership, and far less practical with generally two doors, two seats, and no trunk space. Million dollar F40s are slower than the P85D from 0-75 mph...the speed envelope where 99.9% of driving is done.
The extra range for the 85D is not relevant for most of us (yes, it can be important for some). The Tesla Supercharger network was designed for the 60kWh battery, with far less range than the 70D or P85D. On the very rare occasion that nominal 17 miles might make a difference, your driving habits and your brain will be more important than that 17 miles. And, that 17 miles will become even less important as more Tesla SC stations and direct DC charging stations continue to pop up. Plus, someday, if you really need it, you'll be able to swap out your old 85kWh battery for something bigger...
Don't get me wrong...the 85D is a great car. But the question was why a P85D.