As expected, since I read the reviews here, the staff in the agency tried to sell me an upgrade (even though I booked an SUV, which appeared to be a small City-SUV Renault Captur) to a stronger vehicle and a fuel service because as the vendor said: "There is no gas station around here and I have to pay a lot more if I don't bring it back completely full". He also tried to scare me with a very high retention in case of any damage "even if I don't cause it" although this was already covered by another company, as I told him multiple times.
Not the nicest start into vacations but could be worse.
At least he went through the contract with me in detail.
By picking up the car it turned out that the car was brand new (not even 5000km done) and didn't have any larger scratches. It worked well and could also climb easily even the steepest roads we've found during our time on Madeira. To be fair: A more powerful car would be nice, but is no necessary.
The employees at the returning point were very nice and confirmed me via email that the car didn't get any new damages. So I expect and I hope that I will not hear anything from them.
So at the bottom line:
The car was appropriate and the staff nice but vendor-vice a bit immoral.