Going, going . . .

Running out of fuel is rarely convenient for the people in the vehicle and any others they hold up. This gives me some sympathy for the plan to fine people who get caught short on motorways.

However, while in the past I might have thought running out of petrol was carelessness I’m now wondering if at least some of the time the fuel gauge might be partially responsible.

Petrol gauges in most cars I’ve driven regularly have had a half circle with a hand which moved from full to empty pretty evenly.

My current vehicle, a Toyota Corolla, has ten blocks stacked on top of each other.


The first block lasts 150 – 180 kilometres, the next couple take me around 90 kilometres each, and so it continues with the lower ones taking lesser distances to drop.

The second last one lasts around 40 kilometres and the last one lets me travel about half that distance before the warning beep tells me the car’s out of fuel.

It’s not, but even if I didn’t live 20 kilometres from the nearest petrol station I wouldn’t be keen to find out when empty really means empty.

I’ve worked out that when the gauge shows the car has half a tank of fuel it really has only about a third, but unless I notice when it drops to half I can’t be sure if it has that much or less.

The mechanic who services the car said that was the way the gauges work  and the one in his car, of the same make but different model, also dropped faster as the tank emptied.

It might be the way they do work but it’s not the way they should work.

There’s a visual design fault to start with. Gauges like clock faces have a block of red near empty which reinforces the message you are running short of fuel. Two solid blocks don’t portray the same level of urgency.

Then there’s the lack of connection between what it shows and how much fuel there really is. It’s not so much a gauge as an indicator, and an unreliable one at that. Unless I’m very careful about keeping an eye on it I’m in danger of finding the distance I need to travel isn’t quite up to the fuel available for travelling it.

4 Responses to Going, going . . .

  1. kismet says:

    My subaru has the same problem. I do happen to know it does over 80km with the fuel light on though (that was the point I chickened out about finding how far I could go with the fuel light on)


  2. Motella says:

    I can remember renting a small Jap riceburner with some friends and taking a drive from Greymouth to CHCH…and yes we relised well into the trip that we were running on low.

    Not only did this car have a whizzy electronic fuel gauge (that was soon showing no bars), but it also had a distance to empty indicator. Sure enough this rapidly started dwindling down and we held our breath when it hit zero. But the car kept going and going.

    The distance to empty indicator kept going as well – and started showing a negative distance! We finally got to a petrol station with the distance to empty indicator showing a tad over minus 100kms!

    Ever since that episode I have become fairly nonchalant about car fuel gauges and have assumed that all cars understate the amount of fuel on board – not looking forward to the time when I will be proven wrong!


  3. Richard says:

    You learn sometng trivial occasionally. I did a couple of months ago. Your pic of the petol guage has an arrow, in this case pointing to the left. This is side of the car where your filler cap is. Good hint for rental cars or if you have two cars, are old and get confused easily.


  4. Pique Oil says:

    Most fuel guages are a linear variable resistor on the end of a float. Fine if the tank is a linear shape but useless if the tank is of an irregular shape.
    At best they are indicators.
    Fining people who run out on a motorway is stupid to the nth degree. The only ones who it will effect are the honest Joe’s who will pay the fine. The rest don’t care and will not alter behaviour accordingly


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