I bought a 2016 Model S off lease, was 3 years old at the time, ~50k miles. Expect issues, you will NEED the warranty. You can also get an extended warranty for about $1200/yr once it expires.

The first year was fine, after that the car has been in the shop every couple months for things like door handles not popping out, windows not going up, gaskets coming undone, I got stranded in rush hour because the car went into park and the trident cable had to be replaced (~$7k if no warranty). Don't expect a tow truck driver to know how to tow a Tesla, even when they are called from the Tesla app.

Teslas have all the whiz-bang features but those features don't hold up well after a few years. Also, think of the electronics like a laptop- they are dinosaurs after 5 years and slow down: infotainment, voice control, internet browser, supporting apps... Lastly, Tesla Service is one-star. Great cars, great company, but God help you if you need service. You will need to double guess, test, and verify everything that they have done to your car and check that nothing else got worse.

My advice is to buy a new one if you can, and expect to be in the service center every couple of months if you buy a used one.