Has it ever happened to you that your fuel gauge was reading zero and the car was still running? If so, the first thing you need to know is that emptying the tank is not the best thing for the health of the car. With that in mind, we know that there can be cases where the misfortune of fate causes such a situation. So, if the classic dial or our on-board computer shows us that there is no fuel, how does the car continue to move?
The answer is simple: because The manufacturersThey lieWhy? Because they know that many of their customers are not given to always keeping the tank at a certain level of fuel. After filling it up, the gauge can stay full for a day or two before the needle starts to slide towards empty. Doesn’t that seem strange to you? This is thanks to automotive engineers, who have calibrated the gauges to lie to us. Well, rather to be somewhat exaggerated and somewhat optimistic and not have any surprises.
And like everything in life, it is not the same for all brands, and not even for all models in their line. Some studies and research have shown that meter readings are often, are around 5% error upwardsWhile others can exceed 15% and even reach 20% of extra optimism. While this doesn’t really affect how much gasoline or diesel your car’s engine uses, it could give you the wrong idea of how well your vehicle is performing when it comes to fuel efficiency.
Then you’d brag to your friends about how frugal your car is so they’d buy one too, and before you know it, everyone’s driving cars that lie about their actual fuel economy. But, is it really that bad? Some say no, and that contrary to previous research, on-board computers are probably the most accurate way of determining actual fuel consumption, rather than the traditional method of filling the tank to the top and emptying it almost completely before the next fill-up.
As we will see below, there are a number of reasons that determine the inaccuracy of car fuel gauges, since all of them, without exception, leave the factory without being 100% honest. And this is due to both engineering reasons and conception of the car itself as a human factors because of our way of thinking.
From a technical point of view, why is the fuel gauge inaccurate?
Let’s look at the engineering part and start by explaining how the vast majority of Cars detect the amount of fuelwhat’s in the tank. Typically the sensor is a “sending unit,” made by some sort of float (a foam/plastic cork-like piece or air-filled tube) attached to a long metal rod that connects to a resistor. The system remains attached inside the tank with the aforementioned float bobbing above the fuel. So far, not too much complexity.
Without going into how the electrical resistors that send the signal to the dashboard work, as the fuel level rises, so does the float, and this varies the measurement given to the fuel dial and/or the on-board computer of the car so it can tell you how much petrol is left. However, when the tank is almost full, the float will simply go as high as it can go. It then has to empty a few litres before it starts moving again, causing the gauge to indicate “full” when it is not.
This also happens when the float reaches the bottom, so the car says “empty” even when it is not. Often the range of motion does not extend to the bottom, so the float can reach the end of its travel while There is still fuel in the tankThis is why in most cars the needle empties from below and eventually stops moving while there is still some juice left to squeeze out; we stress again that it is not advisable to empty the tank to the last drop.
Another possible cause of inaccuracy is the shape of fuel tanks. On today’s cars, they are all plastic, moulded to fit into very tight spaces in the chassis. Often, the tank can be shaped to fit around various body parts or the frame itself. This means that by the time the float reaches the midpoint, there may be more or less than half the fuel left in the tank, depending on its shape. And the inclination the location of the car also influences.
Why is this inaccuracy done on purpose?
Psychologically, this might bother some people, as it makes the fuel gauge somewhat inaccurate. However, here’s the thing: we drivers, We like it better this way. Thanks to modern technology, we can tell exactly how much fuel is left, don’t we? We don’t really want to run out of fuel when the dial is on the “E.” Apparently, we want to have the reserve so we can panic and drive on a dime to the nearest gas station.
Similarly, it apparently makes us feel good to have the needle on “F” for longer. In part, this is because It gives us the illusion that we are getting better consumption and the car is extremely efficient.And it also makes you feel like you’re not immediately burning through that deposit you just spent 50 euros on (even though you totally are). The idea is similar to setting the clock forward 10 minutes so that even though you know it’s not exactly the right time, it somehow motivates you to get out of bed earlier.
The difference with the fuel gauge is that those 10 minutes difference are not a choice on the part of the driver. We are stuck with gauges designed to make people feel better, not to accurately inform. While customers want a reserve to be available when they reach the empty mark, technically there is no such reserve, it is simply a matter of time. there is an actual empty spot that is not marked on the meterAt the same time, customers don’t want too much reservation. There seems to be a sweet spot where customers are happy to be cheated, but also not too much.
How to know how much fuel you actually have left
You may be surprised at how much fuel you actually have left when it looks like there is none, according to the gauge. To find out, check your owner’s manual, for know the exact volume of your fuel tank.
Then, the next time your gauge shows empty, find the nearest gas station and fill up. Subtract the number of liters needed to fill the tank from the volume indicated in the manual and you will know how many more liters you can have when the gauge reaches zero.
