Had a negative experience renting from Centauro via Economy Car Rentals due to the mandatory 25€ "refuelling charge". Basically, you are charged for the fuel up front, and can return the car with as much fuel as you want, they'll refund the difference between what they charged and what you have and will charge you 25€ on top. It was spelled out but in tiny print in the Ts and Cs of ECR, so do be careful and avoid centauro.

They're listed as located near the airport with a shuttle, but they're actually located near Oriente, so you'd probably get them when renting from Oriente too.

Thankfully most of the time you can see who the provider is after booking, and cancel the booking if it's not too close to the booking date.