I used to work at Enterprise, so can make a few comments on the above.
Starting with fuel, well if you have 100 cars, with an average of a 50 litre fuel tank, then that works out at 5,000 litres of fuel. That works out at £5,500 sat in fuel tanks that you can's use elsewhere. Enterprise have over 10,000 hire cars in the uk, so that would be half a million pounds in fuel, sat in cars that someone else is using. And if they come back full when they are to be sold, that would be £500,000 given away.
THerefor they work on a 1/4 tank policy - each car should have a 1/4 tank minimum.
Some corporate customers require a full tank, which is why you will get them with more. Enterprise don;t like doing this, as it costs them money, but are kind of forced into it.
With the damage side, every member of staff is completely different with their attitude to damage and what they mark. Always make sure you check the car and that it is clean. Also make sure that you know they are happy with it when you take it back. I have had people walk round cars with video cameras beforre, naturally people are sceptical about it.
On the whole, you should be ok, but every now and again you will get a car which has damage which is not logged onto the computer system. This is where a problem s caused, because it can't be attributed to a renter and so the repair cost is given to the branch where the car is. And that means someone higher up the chain asking questions, which is not good.
You will tend to find that the people who abuse hire cars the worst are the staff. The get to know what they can do in them, drive themn for short spaces of time, and know that if they handbrake a car, do a burnout or hit a speedbump fast they will probably never drive the car again.
You do get people who really abuse the rental cars, and that is to be expected, but most people would treat them well. Because we would provde courtesy cars through insurance companies, you would rent brand new cars to people who (like me) could/would never own a brand new car. I used to love seeing the looks on peoples faces because they really felt proud that they had this car, even if it was only for a week. And they would make sure the car came back spotless.
The worst renter was the one who figured that the car was crapper than their own, and it wasn't theirs so treated it like crap.
With regards to the comments above on feeding info back to the insurance companies, it was swings and roundabouts. On one hand it is of no importance to us what the customer has told the insurance company, and if a customer told me a tale about what happened, I had no evidence to say what they had told me was true. But we would look at getter customers a bigger car if they had a non fault accident (££££KErching). So that info would sometimes be passed.
More commonly we would come across driving license discrpancies. We wouldn't check if it was just 3 or 6 points, but depending what the offence was we had to check the insurance company knew about it so our car was insured. these would be things like dangerous or drink driving. Also the number of people who have been banned, but not reapplied for their license was scary. When one guy wo had not reapplied got told he would not get a car, he threatened to ring his insurance co and complain. I handed him the phone and said that he was more than welcome, but then his own car wouldn't be fixed, as they would then know he didn't have a license.
I have had older customers who had insurance claims going through but their licenses have expired. One lady needed the car to see her husband in hospital, but ha dan expired license. As you can imagine on this occasion, I advised her to re apply, not take the courtesy car and not tell her insurance. I did not tell the insurance co.
Hope yo uenjoyed this little view into the world of car rental. And yes, I did enjoy getting to know how cars really handle......
I thought you hadn't been to London recently 
