What Side of the Car Do You Fill Up On?

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Motoring mystery solved Inventor of that triangle that tells you what side to fill your car up on revealed

Most of us have been in the situation where we pull up to the pumps at the forecourt and we are confused as to which side the petrol cap is on.

We may find ourselves looking in the side mirrors to see if we can make out which side the cap is on. Some of us may even decide to pull close to any one of the pumps so that if we have chosen the wrong side, we can still pull that pipe around to the other side of the car, hoping that it reaches.


Often not known or overlooked by most motorists, is probably one of the most useful indicators on your car and that is the little pointing arrow on the fuel gauge icon which tells you on what side to fill up your car.


Petrol Pump side indicator


On the fuel gauge. A little, unlabeled triangle, usually right next to the petrol pump icon. For those of us who know about it, this little indicator is very helpful, especially if you drive a number of different vehicles.


This indicating arrow remains extremely useful as there is still no general consensus among car manufacturers as to which side the fuel tank should be on, so the arrow is particularly helpful to renters and new car owners. But whose idea was it?


Well, one rainy day in 1986, a Ford interior trim engineer named Jim Moylan was driving a company pool car that he needed to fill up. As with many drivers, he first went to the wrong side and got soaked in the rain and as they say, necessity is the mother of invention.


Motivated by the incident, he shared a memo with his supervisors suggesting that there should be some kind of indicator added to the gauge to show easily which side to fill up on. Jim soon forgot about it but three years later, it turned up in the 1989 Ford Escort and the North American Ford Mercury Tracer.


This tiny indicator was eventually adopted by all other car manufacturers all over the world over, even though no there are no regulations that require it. Even though this little arrow idea was a spark of genius from Jim Moylan, the concept may have turned up a decade earlier.


During the mid-seventies, the low fuel light located inside of the fuel gauge of the 1976 Mercedes-Benz W123  was shaped like a triangle and when lit up, also pointed towards the side of the car that you had to fill up on, with Mercedes unable to confirm the reasoning behind it or if it was a deliberate rationale. Instead, the first documented use of the symbol for the fuel filler location was in 1997.


Jim Moylan didn’t file a patent on the design, but he’s happy to point it out to anyone who looks like they need it, never taking credit when he does.


Justin Kavanagh
Justin Kavanagh is a recognised leader in automotive intelligence and vehicle data supply to the entire motor industry. He has almost 20 years experience in building systems from the ground up. As the Managing Director of Vehicle Management System, he understands the need and importance of trustworthy and reliable vehicle history and advice to both the trade and the public.
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