I'm new here but there is no tank calibration feature other than in the measuring device that is set in the initial design and/or firmware. All tanks are the same shape for this car, so those values are fixed. It is usual to give a 50km average allowance in modern vehicles that equates to 30 or so miles but it seems there is around 10 litres for the CT, so that would equate to about 100 miles. This does seem a lot, so it would be nice to have some clarity here!