Next time you’re lost in boredom at the petrol pump, think about this. Several metres below you are three massive storage tanks. Two of them contain regular unleaded petrol - one with the highest octane grade of fuel, the other with the lowest - and the third holds diesel.
When you select your fuel grade and pull the trigger, suction pumps inside the petrol dispenser draw up fuel from both the high- and low-octane tanks and blend them to the precise octane level. A spinning ‘fuel-Ometer’ inside the pump records how much petrol flows past, keeping track of your purchase. Since petrol expands and contracts with hot and cold weather, a temperature probe compensates for fluctuating volume, ensuring you get what you pay for.