At Adelaide Hills Touring we DON'T take any security deposit, we DON'T put a hold on your credit card. If there is an accident or any sort of problem we work with you to resolve it. So far we have had 2 cases of very minor accident damage to our cars. In both cases this has been claimed on the customer's excess insurance without any problems arising. Accidents happen, and that's what insurance is there for.
We did have an engine failure in the Porsche early on, but that's a risk in any 15 year old car. There's no reason to think that our customer in that case was driving any harder than is reasonable. Sometimes stuff just happens. Fortunately it was right at the end of the rental, when the customer was on the way to fill up the fuel before we collected the car, so the customer was not inconvenienced. We certainly didn't suggest that the customer was at fault, or in any way liable.
We've also had a few minor breakages, like sun visor mirror covers and door locks. That seems to be just a matter of unfamiliarity with a different car, and probably some weakness or brittleness in ageing components. We don't see that as being the customers fault or problem.
We do ask that our customers treat the cars with respect, and by and large, they seem to do that.
Most importantly, when someone rents one of our cars we want them to relax and enjoy.