Numbered Cars

I was looking at the number plate of a car parked outside my house - S208VBJ.

Using my special code S208VBJ adds to $65$.

They all also add to $65$ using my code!

Using the code you treat every character, that is a digit or a letter, as separate.

Numbers are simply added together so that, in the first number plate $208$ is $2 + 0 + 8 = 10$.

Letters are translated into numbers in an organised and systematic way. That means that if you know the value of F and H you not only know the value of G, but can easily work out all the rest of the alphabet.

Can you crack my code and use it to find out what both of these number plates add up to?