Hesitant first time buyer, Tesla 3 range at 80-90mph?

Hi, I am thinking about getting a Tesla 3, probably the long range one. The range they quote I presume is at 70mph, but on a long "autobahn" journey I might well cruise at 80mph or even touch 90mph for considerable lengths of time especially if driving on a dry, clear night late on. Does anybody have experience of how much the range reduces? I don't want to be doing a 200 mile journey in 2½ hours then have to charge for a ½ hour so I can do the last 20 miles...
What do people think of long range travel like that in a 3? Is the S better? How do both of them compare to, say, an S class Mercedes?
Many thanks