I just completed my 10th Sixt rental and it was not great. I needed a full-sized SUV with maximum cargo room for my trip. I reserved both an FFAR and an XFAR, at the recommendation of a phone agent. 2 days before the rental I called the local MCO office to inquire about putting in a preference for a vehicle. For FFAR I preferenced a Suburban and for XFAR and Escalade. The next day (day before rental) I called two more times, and spoke with two people who said they would be "sure" (their word) to "hold" one of the two preferred vehicles for me. They said that since they KNEW I would be coming, they could "do that" for me.
I again called on the day of the rental before my flight to MCO and they said they had both vehicles and would hold an Escalade for me (which was my first preference.) Lo and behold, I get to the check-in counter several hours later, and they have ZERO full-size FFARs of any type, let alone a Suburban, and when I inquired about an Escalade, the person checking me in said "Ohhhhh, someone JUST upgraded to one about an hour ago" (salt in the wounds) and on top of that they had no XFARs left either.
This was very frustrating, because I had called on over 3 separate occasions leading up to the rental and was told I would have one of my two choices held for my arrival, and when I got there not only were they not held, but they were completely out of any cars in my two categories, and had allowed someone to upgrade to the last XFAR, when I had a confirmed reservation for one just an hour later. To add to that, when the person checking me in realized he didn't have any Tahoes, Sequoias or Suburbans, he offered me a Chevy Traverse and claimed it was a full-size SUV. I had to pull out the Sixt app on my phone to prove to him that it was, in fact, not.
The only reason I ended up with my reserved class was because a GL450 happened to pull up as I was checking in. This car was lacking in luggage space which was my primary concern and why I had called to try to ensure a larger vehicle. Two passengers ended up with roller bags on their laps for the two hour drive to Jacksonville. My first few rentals with Sixt were great, but it's starting to lose its luster a bit. I think I may have to switch to a company that offers Suburbans as a separate class, so that I can have that luggage space assured.
I guess there isn't really a question in this post but I just wanted to share that experience.