How far can you drive on an empty tank?

Thursday April 15 2021
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By Mustafa Ziraba

Before letting your car run on empty again, it is worth knowing just how many or how few kilometres you can actually drive after the light comes on. It is also smart to know what else is at stake when you let your fuel tank run to near depletion.

The fuel tank is getting low, perhaps the gauge is now pointing to “E” and the little light illuminates. How much longer do you have before you require the services of a boda boda to get some fuel in a jerrycan? The detailed answer depends on all sorts of variables such as the age and model of your car, how much weight you are carrying, and what kind of driving you are doing. The more fun answer is to find out the hard way.

What the light means

The interest in the low fuel warning light is strengthened by the fact that few people have any idea what it really means when the light is on. As expected, car manuals shall tell you how much fuel is left in your fuel tank when the low fuel light illuminates, that is to say what the size of your reserve is. Problem is, many being second, third or even fourth or fifth owners, car manuals are hard to come by. For cars from Japan, these manuals are in Japanese. Unless of course you spent some time in Japan, such a manual would not be of much use.

Many newer cars go ahead to tell you conservatively how many kilometres on average you have left depending on your driving style and how much fuel is remaining in the tank. This range of course changes drastically based on acceleration demands. Additionally, you have to remember that these newer cars’ fuel gauges are extremely accurate. When the needle is at E, you better fill up.

Some people are just less inclined to enjoy surprises, especially when they involve getting stranded. So, they start to panic when the fuellight goes on. The amount of fuel left in the tank when the low-fuel warning light is on varies greatly from car to car even within a particular model line. When I was younger, I would flawlessly drive huge distances when the needle was below the “E” in a Toyota Wish. Also, we have to note that the fuel gauge is not exactly the most precise instrument because of the inherent mechanical inefficiencies. Some gauges are so bad that the fuel light oscillates between on and off depending on the car’s gradient. Some do not move linearly but make step movements.

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Reserve tank

Most manufacturers by and large have generous reserve tanks. There is no standard for how big the fuel tank reserve is, but most of the time, it is about 10-15 per cent of the overall size of the tank.

The amount of fuel on average for most cars can get you another 20 to 70 kilometres after the fuel warning light illuminates. That is of course if you are not in an ego testing race on the highway with some stranger.  When the light illuminates, I would recommend that the driver employ fuel saving driving practices immediately and refuels as soon as possible. The size of the reserve is logically proportional to the engine size. And some cars really mean business when the fuel light illuminates while others are a little friendlier.

Measuring

Most modern cars have a distance to empty gauge on their instrument cluster, which provides an approximation of how many kilometres can be driven before the car runs out of fuel. Many people prefer to use this feature in lieu of the low fuel warning light, figuring that if the gauge says there are 20 kilometres left, then they have 20 kilometres before they run out of fuel.

However, if you really have to find out how much fuel your reserve tank has without the car manual, drive until the light illuminates, then immediately stop to fill all the way up and then comparing how much fuel your car took with the tank’s capacity. Once you repeat this process a few times, you should have a fairly good estimate of how much fuel is left after the fuel warning light illuminates.

Downside

One thing worth mentioning, though, lots of electric fuel pumps are very fussy about being run dry, and can burn out if you run out of fuel too often. So, while it is okay to take some risks, it is best not to have that pump sucking air or debris at the bottom of the tank.

Exactly how far you can drive on empty depends on your car, your driving habits, and road conditions. Simply said, if it illuminates, you should be able to finish up your errands and refuel when it is convenient.

Ideal. Experts say you should keep your gas tank at least a quarter full at all times. Obviously, doing so will keep you from getting in a dangerous situation where you are low on gas and too far from a gas station to fill up, but there are other, less obvious reasons to keep a little gas in your tank.

Why avoid driving on empty

Driving on empty can damage to your vehicle. If you run out of fuel, you can do damage to your catalytic converter, which may then need to be repaired or replaced as a result. Even the simple act of driving with a low amount of fuel in your tank can damage your fuel pump, as any debris or contamination in the gas (which naturally settles at the bottom of the tank), will be sent through your fuel pump when the tank is nearly empty.

Note: You are not going to ruin your car the first time you drive it with the low fuel warning light on, but it is a harmful practice to do regularly.

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