Progress by the dashboard light

Imagine your car didn’t have a dashboard and, instead, as you arrived home in the evening, it printed out a report of your day’s driving. The report tells you the speed you drove, the distance travelled and provides detail on fuel consumption. You note with alarm that your maximum speed was 60 miles per hour when you spent all day in a 40mph zone. And you also notice you are nearly out of petrol, and don’t have enough in the tank to make it to the garage in the morning.

If this kind of post-trip