6/2 The gas arrow

Ok, I write this with the risk of looking like a complete idiot. However, I have it on good authority that I'm not the only one who did not know of this awesome invention. Sometimes car manufacturers have an epic win.
I recently found out after reading the 1000 awesome things blog that there is a trick to always remembering what side your gas tank is on. Now, I'm pretty good about it but I still second guess myself. We have two vehicles and the gas tank is on the opposite sides of each other. But apparently, some cars have a little arrow that points to the side where you fill up at. Now if you don't have an arrow apparently the trick is which side the gas pump is on the little drawing. Well the next day after I read all this I hopped in my car and had to gas up, and wouldn't you know but there was that sweet little arrow looking right at me :)
So here's to the gas arrow! cheers!

So..did anyone know about this? And if so, why have you been holding this secret?