Not sure if they charge more for fuel long time since I checked. With Brunos I used to have a choice whether to return full or empty, I think I then choose to return full as running around with a tank running low on your way back to airport is risky.
Its better to say give it me full and not charge for fuel and I return it full. I used to fill up at the garage next to the airport its about 200m from the entrance to the car park.
I now have my own car that I leave at the house, I used to use Brunos loung term parking at the airport but the compound has been compulsory purchased by the airport last October. So I use Brunos for a 1 day hire that only available for their ex. long term parkers, I check the fuel gauge and fill it back up to the same level. I use this both ways and leave the car at the house now.
If they get some more land for parking I may go back to parking at the airport again.....however the two one day hires are about the same as parking from a cost point of view.
I plug in a solar battery charging panel (about £20 from Maplin) thats keeps the battery trickle charged when the car is not in use this stops the alarm system/central locking draining it which it will do over a long period 8 weeks plus.
Which ever company you use if you use them on a regular basis they occasionally bump you up a group on the car for the same price when they run short of cars in the class you have booked.
Brunos is one of the smaller companies so you reach that status quite quickly, plus they are in Duquesa so if you have a problem they usually have spare cars nearby and you go into the office if you have problems speak face to face.
My neighbour has always used Crown.