Where did you come up with 0.83 per km rate? That is way in excess of any government approved mileage rates and, in any case, does not address the problem of incomplete record-keeping by the Uber driver. I have mentioned before that this is a business and, as such, it is incumbent on the business owner to keep detailed records of all vehicle and other expenses. On top of that, detailed records need to be kept of the use of the car on for both business and personal purposes.