I heard something interesting today: reversing into a parking space, or onto your drive can save you up to £100 a year in petrol.
Apparently it's because a cold engine can use up to 4 times as much petrol than a warm engine. So naturally you want to get things warm as quickly as possible without wasting fuel and what better way than en-route to your destination?
It's not likely to make much difference if you're just popping into the shops for 5 minutes, but if you're going to allow the engine to cool down, I can see this being really useful. That said, surely reversing into a spot when you can just drive through is going to use unnecessary petrol as you cover the same small bit of ground two, three, maybe even four times, depending on how good you are at reverse parking.
So here's a money saving tip: get to work early or park at the far side of the car park so you can drive straight through a parking space so you don't have to reverse at all. If you have to reverse, keep it to the end of your journey when the engine's already warm.