While $821 may be the answer as stated, I'd add even more to it, because you need to also subtract out oil changes. But to be honest, you will want to prorate the cost of the charging infrastructure that you had to install to charge. But in any case, it is still probably over $500 per year.
Or in the case of Model S and Xs, as well as the Nissan No Charge to Charge, and maybe even work provided charging, the answer may be as high as $1450!!!