I heard there was something like a sensor under the seats which can detect when a passenger gets in and hence keep a log of miles travelled with passanger.

Is that true?

Regarding the rental scheme, i thought it was unfair on the drivers but reading here about the drivers not turning meters on, guess the management dosen't have a choice.

Another out of the box idea would be for the company to offer customers some sort of reward scheme so that it is in their interest to demand a receipt. Perhaps something similar to the airmiles scheme that airlines have.

cheers