There was no 7-seater Mercedes van at the Hertz location in Frankfurt Airport, they gave me a Ford instead. When I wanted to switch, the staff said it was the only option, and it was diesel. Very frustrating. The staff was enthusiastic, but it felt fake. They pushed for full insurance, about 40 euros per day. When I went to pick up the car, the man there was really irresponsible, just reading an e-book and not helping me find a child seat. When I found out there was no child seat in the car, I went back to him and he finally got one for me. He asked if I wanted a booster seat, and I thought, I paid an extra 55 euros and this is what I get? In the end, I chose a child seat for ages 3-12 (not an ISOFIX one, just secured with a seatbelt).