Using sixt.com, a reservation from Munich City Center Sept 10-18 produces a prepaid price that is more expensive than the flexi tariff. 328 euros prepaid versus 268 flexi. That seems backwards to me.
I've varied the location, and this happens for several stations in Munich as well as Nuremberg. If I change the dates to Sept 9-16, prepaid is less expensive. So it seems that prepaying for dates that include Sept 17 or 18 are more expensive. I could understand if rates go up around Oktoberfest, but shouldn't the flexi rate increase as well?
More confusing, this doesn't seem to be the case on sixt.de.
I'm concerned that if I make a reservation with the flexi tariff, I'll find a surprise when I arrive at the counter. Thanks for any insight you can provide.