Hi everyone,
Last year, I bought a used (from Tesla directly) 2017 70D model X, supposed max charge 237 miles.
My battery seems to drain very rapidly. It will only charge to 212 miles
I think you mean X75D? I don't believe any of the originally planned 70's were ever actually made. Yes the 75's were originally supposed to have a maximum of 237 "rated-miles" of electrical storage capacity in their battery packs. If you set your car to charge to 100% full and, after it successfully finishes charging, it only displays 212 rated-miles, well, that's not wonderful, but it is "normal". When I sold my 75D a year ago its max charge was 214. That's about 10% off its original capacity after 5 years. Entirely normal.
and on top of that I consistently use up 1.5-2 miles of battery per 1 mile driven.
Yes. This also normal. At least in winter. If your car gets cold overnight and you only go on short trips during the day, you will probably only get 1/2 to 2/3 as many miles as what the dashboard display shows. That's why we think of them as "rated-miles" not actual guaranteed miles. To achieve the EPA "rating" you need to have perfect conditions like moderate speeds, warm weather, warm battery, no rain, no wind, light load, inflated tires, level ground, don't use the heater, etc. Any departure from any of those things means you'll fall short of your "rated" range, often by quite a bit.
Additionally, it will only charge max 150mph at a supercharger. Takes forever!
As somebody else said, make sure you are at the fastest kind of supercharger. Also you say it will "only" charge at a certain max rate, but supercharging speed can be quite variable, even within the same charging session.
You'll want to be sure you have observed it in all kinds of different conditions first before deciding what its absolute best performance is. It would be unusual if your car couldn't briefly reach 300 rated-miles-per-hour , or at least the high 200's, in perfect conditions.
Perfect conditions would require arriving at a supercharger at a very low state of charge (ie battery almost empty) fully warmed up (ie after having driven a very long time to *get* to the supercharger) and of course the supercharger itself must not be limited, either because it's the slow kind or you are sharing it with some other Tesla parked at the charger immediately adjacent to you. If you are certain you have achieved these conditions yet the car only charges at 150 rated-miles per hour, yeah, that's a little surprising.
To spell it out a little more, even if you arrive with perfect conditions, the charging speed gradually drops as the pack starts to get full. So just because your car should be able to touch 300 rated-miles-per-hour briefly doesn't mean it can *sustain* that rate. No Tesla can. If you are determining your max supercharging speed while trying to top off an 80% full battery, it will always look slow. Supercharge when the pack is low for best results.
I hope some of this helps set expectations.
You'll have to post pictures of your dashboard displays if you want more specific feedback.