I've got all my mileages recorded accurately (and indeed I did use google for one of the calculations). some trips were made in my own car and others were made in rental cars of different types. I know that different cars have different fuel consumption etc, just wondered if there was a flat rate for tax purposes. I've just done them all now at the aforementioned 0.7 per km, so at least I now have a total in my little boxes !!