Why are you half price than booking directly with Sixt?
Sometimes, that can happen as car hire companies like Sixt allocate vehicles at a discounted price to us each year. This may be also of interest to you:-
YouTube - Subscribe for free, to a new forthcoming YouTube channel for discounts and tips on a stress-free Car Rental experience.https://www.youtube.com/channel/UCNdcTFzsRBAHxobnfp65M9Q Be one of the first 100 subscribers, to obtain a introductory discount on your next car rental.