I bought a '15 S 70D w/130k miles on it 8 months ago. It had 10 months of warranty left, so I was taking a calculated risk since you can't get any previous service history. Tesla won't give it out.
It has the usual degradation, but so far no battery or drive unit issues.
In a couple of months, I'll have to make a decision whether to get an extended warranty, like from 057Tech or risk it.
Another thing you should consider. How handy are you? Do like working on cars? What's your comfort level with doing minor maintenance yourself? Can you watch a few YouTube videos and typically be able to complete tasks?
Because that will save you some money for all the little things that aren't warrantied.
I've already repaired a door handle, replaced an instrument cluster, replaced a headlight bulb myself. Those are not cheap if you have to take it to an SC each time.
But I like to tinker, so I've also done several things just because I wanted to, like swap the interior dash trim from Obeche wood to CF, swapped upper B-pillars from textile to Alcantara, upgraded the interior lights to brighter LED's, chrome delete, etc...
I say that not to brag, but to say that these are a more high maintenance vehicle.
This forum has helped me immensely with getting recommendations and how-to's for my projects. So I try to give back when I can.
You'll find most of the folks on here are the same way, and we didn't buy a Tesla to just drive from A to B.
If you're looking for a straight commuter, and are just trying to avoid the gas station, Tesla isn't for you.
We're not necessarily gearheads, I know I'm not. But I like beautiful cars, and I'm willing to take the good with the bad.
Like some others that posted, I think the '16 refreshed 75D would be the better option. Even my 70D has plenty of performance. And the drive units share more of the load which seems to make them more reliable in the long run.
You get the newer nose, the range will probably be about the same as a P85D since the rear drive unit is smaller.
It's more likely to have MCU2, possibly full AP1.
Just my 2 sats. Ultimately, it'll come down to your preferences. I wish you luck, and enjoy whatever you choose!