That's standard procedure here. It's called Tageszulassung (one day registration): Dealerships register new cars on their own name for one day, so they're able to sell them as "used". This allows them to sell the car with a higher discount than they're normally allowed to, according to their contract with the manufacturer.
For the customer it means they get a better price, but otoh they have to take the car as it is and can't choose which extras they want. For the dealership it means they can sell more cars, making them eligible for bulk discounts themselves. And the manufacturer is also somewhat ok with that because they sell more cars without being forced to lower the catalogue price.