We are looking for a used MS too. Ideally a 85/90 variant. From my hours of research so far I am struggling to understand how you can assess objectively the condition of the battery ie both its current capacity and whether charging rate has been throttled or might be in the near future? I don't want to buy a car I'm expecting to take x mins to supercharge only to find it takes x + 20 or worse down the line. There appears to be no resource available to find out for sure and Tesla are hopeless if you phone them and you are not the owner.
Is the 75 battery affected by these battery/charge-gate issues? What about the 100? Thanks.
Are there any 100 cars out there that came with free supercharging for life?
Although there are some that would not agree with me, I personally would be inclined to buy (as we did in the end) from Tesla's used inventory. The warranty has more than returned any premium we paid and with fears over MCU1 longevity, its value may yet be relied upon again. I hope it will also help support the resale price if we sell before it expires. Although I have no proof, kinda think Tesla wouldn't pass on a car with a throttled battery. I also suspect that being a Tesla-supplied car the service centre go the extra mile - as they have with us. But that's all speculative.
One problem with inventory used cars (CPOs) since we bought ours last May is that cars resold by Tesla are now stripped of free supercharging for life. But is it really that valuable? Let's say you use 1000kWh of supercharging a year; that's only £240.
Most complaints do centre-around the 85 battery. Ours is the 70 (same cell chemistry) and while supercharging has slowed a bit because of re-profiling of the charge rate by Tesla, it wasn't mega fast to start with as 70 batteries are 350V instead of 400V. But its pretty clear that no matter which battery, if you abuse it then it will get throttled eventually. Our 'Typical' miles range has only dropped 1-2 miles in 11,000 miles, but we only use supercharging for long trips (reached almost 900kWh in 11,000 miles vs 3400kWh AC charging mostly at home @5p/kWh - about £170).
If you really must have free supercharging for life then Richard Symons in Bournemouth comes highly rated (not very convenient for you in Edinburgh!) for used Teslas. I would not buy from a non-specialist 3rd party dealer and even some that do specialise in Tesla look dodgy.
PS I forgot - not only is free supercharging stripped from Tesla resold inventory but so is the free 'premium' mobile data connectivity - you only get 30 days worth.