Not sure if everyone else knows this, but it would explain the 'female drivers' looks I'd get when at the servo driving someone else's car.
On the fuel gauge there's a petrol bowser symbol. Whichever side of the gauge the symbol is on, is the side the cap for the fuel tank is. When I learnt that I went and checked our cars, both Toyotas. They even had a little arrow pointing in the right direction! The number of times I've had to get out to check where the cap is, and it was staring me in the face the whole time! Felt like a wally