We just bought a Tesla Model S. The delivery manager suggested that we take the pre-paid service plan ($1900 for 4 years or $600 for each annual visit !!!!) to avail of modifications Tesla makes to the body of the car, in addition to regular maintenance. Is this really true? What sort of maintenance have you had to do on the car? Do we really need to go to the Tesla service center for servicing / annual tuning? I have not taken the buyback option. Thx in advance for your help.