Thanks. I will go later in the spring for another test drive, hopefully for a multi-day drive so that my wife & I can have time to get comfortable with the car.
Did you get any details about how they got to $1600? Did you get your plates from a Hennepin County service center or did the EP store take care of everything? Assuming you went during the month of January to get your tabs & your Model S is a 2016 model, the base values chart only goes up to $99,999 vehicles and shows $1259 as the registration tax for that bracket.
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Here is the link to download the tables from the state.