Hello everyone,

I'm flying to the USA in July and am renting a car from Sixt.
As the route will be a bit longer, I would like to book my girlfriend as an additional driver.

Is it "better/cheaper" if I book the additional driver online, or should I do this when I get there?
If it helps, I have the german Amex Platinum . (I know that additional driver are included in the us platinum card, but not in ther german cc)

Thanks in advance