I am a driving instructor, and can only get around 10 hours of tuition from a tank of fuel in the Jazz, so if I am busy, I need to top up again each evening to get me through the next day. I know its only £25-£30 a time and it all equates to the same thing, but it just annoys me too that in theory theres 15 litres of fuel constantly sitting there that I don't have the bottle to use.