I travel to Las Vegas frequently, and noticed in December that they were working on the building just across from the car rental center. When I returned my car it was already finished (late December), and the signage was already in place for me to recognize it was Sixt. I've known Sixt for years from Europe, and have rented with them in Florida as well.
I checked the webpage and found they have really nice cars at really ridiculous prices. Since I had to travel again last week, I booked through them.
First off, let me tell you this is not just about the cars anymore. The building they've got is HUGE. Amazing. When you walk in (or get off the Mercedes Benz shuttle they've got... I walked with just my carry on), you get greeted by an ASTONISHING beautiful lady (guys are really nice too), who takes your luggage and offers you a drink. No kidding. You feel you have just walked into an airport VIP Lounge. Nice sofas and everything. And if you remember, check the restrooms... I mean... this is a car rental company... I wasn't expecting this.
I had rented an FCAR for 3 days, and ended up upgrading to a BMW 328i with 2K miles on it for $20/day (they also offered me a V8 Charger RT, 16 miles on it). Ended up paying $197 for a lovely car.
Returning the car was easy; they drove me to the car rental center to take the shuttle in the same car I drove, so no hassle with the bags.
Overall, I had a really nice experience, in a really nice place, with staff that makes their best to try to give you a memorable experience. Again... I wasn't expecting much, and got surprised.
Good luck with yours!