Why dont cars display 'fuel remaining' data: Is it complex to implement

The location of the float and the comparing it with total volume of the fuel tank should give the fuel remaining.

BHPian kavensri recently shared this with other enthusiasts.

I always had this question in my mind. I searched the internet to find the answer and I am somehow not convinced with the answers provided there.

So, I thought of asking the same here.

From what I understand, detecting the 'remaining fuel quantity' data could be much more complex. But is it that complex to implement with the latest technology/sensors?

Here's what BHPian KarthikK had to say on the matter:

Range left in kilometres is a direct derivative of fuel left in the tank, and most modern vehicles have the distance to empty or range number built into the console options nowadays.

Litres left in the tank is not a direct indicator of how important the number is to the driver/rider, range is a more usable number in my opinion. 5 litres left in a 250cc bike tank can mean 150km range, same 5 litres left in a petrol luxury sedan will mean 20km left .

P.S - some vehicles have an option of showing fuel consumed in litres for a tripmeter distance. So the data is there from the sensors, it is probably just about manufacturers showing usable and easily understandable parts of that data

Here's what BHPian ashis89 had to say on the matter:

The location of the float and the comparing it with total volume of the fuel tank should give the fuel remaining. But when the vehicle is tilted or moving on uneven ground, the float won’t receive the correct measure.

(Fuel input - Fuel output/consumed) seems the most accurate method but I am not confident how advanced/accurate a sensor can be to measure fuel input. Input would depend on fuel nozzle size and the speed of delivery. Need to account for evaporation and leakage. Doable but is it worth the effort?

I find DTE meters to be inaccurate.

Here's what BHPian Turbanator had to say on the matter:

I will agree, based on the car Say I am driving my sports car the way it is supposed to, and the range shows 90Km, and I know the next fuel pump that has XP-100 is at least 130Km away, so if I know I still have 20 Ltrs left, instead of DTE, I can drive the car more sedately without worrying too much. Of course, currently, the DTE changes in real-time on most premium cars, but the value of actual fuel can be more comforting.

So why are the gauges not available to show this is probably because most people will be keen to know how far they can reach and not necessarily do the calculation of fuel left x average mileage they are getting, and knowing the actual mileage in the last few km will be pretty tricky.

On a regular car where the average mileage does not deviate that much, one is better off with DTE, hope this helps.

Here's what BHPian ex-innova-guy had to say on the matter:

Toyota is generally known to be reliable, but my Innova once left me stranded due to the DTE figure shown. I have a habit of refuelling whenever it drops below 90 km. One day I didn't follow that and was going to refuel around the 50 km mark. Car died on me when it had 60 km of DTE left. Just a minute before, I could feel the throttle response lagging, and the next minute, the car died on me. I had to call my dad, who was 10 minutes away, and soon called the SA. He advised checking the fuel pump condition, and he diagnosed that I had essentially run out of fuel! After getting an earful from dad, I went on to the nearest fuel bunk and refuel it. After refuel, had to keep pumping the fuel motor to start the car. A good lesson to never rely too much on the sensors!

Here's what BHPian Redex had to say on the matter:

Simple, distance to empty. Refill when you have at least 100km range left, unless you know your next filling station is further than 100km.

Other data i.e. litres left, fuel consumption rate ec etc are all pointless. All you need to know is how far can I go.

Why take the risk of running out keep the tank at least 1/4 full. You never know if your next fuel station is open or has run out of fuel. In that case you still need enough fuel to reach the second fuel station. Can't do that if you only have 3 litres left !!!

You never know if you might need to make an emergency trip to take a family member to hospital. Oh dear got to stop and fill up with fuel because I only have 3 litres left.

In my car a 1/4 tank full is good for nearly 150kms. I just won't take the risk.

Here's what BHPian Freespirit had to say on the matter:

Fuel remaining and usable fuel are two very different figures. Aviators will tell you the criticality of the two! For a very layman explanation, depending on the construction of the tank (more applicable to metallic tanks and my guess either due to design- the center tube or frame member, in bikes and to prevent rusting in a empty/ dry tank, in case of cars) there will always be some unusable fuel in the tank. This may not be measurable accurately depending on the height of the pickup head/ inlet. So whilst fuel remaining could be calculated based on tank volume, the usable fuel may not be so simple to calibrate.

I know of a case where someone borrowed and ran a 2nd gen Honda City of my friend, to low fuel level. Since my friend was out of town and when he got back the car wouldn't start and had to be towed. The ASS said there was rust in the fuel pump (due to it being run-dry and left unattended) and a hefty premium was paid to get it changed. The DTE in modern cars always caters for a reserve and is more of a warning sign than a, 'Try and prove me wrong!' sign, so general advice react to it in time rather than challenging it. Bottom line fuel remaining does not directly translate to range remaining.

Here's what BHPian Zippy_wheels had to say on the matter:

For some VW cars, the option is there, but disabled. I got it enabled but I dont use it much. I dont have it enabled as a default selection in the MID. The only time it comes in use is when I go to a pump to refuel. If I am not in a rush, I enable that view, and compare it to the actual fuel the pump operator filled. Its not accurate but helps me confirm that I was not cheated outright by the operator. Say MID shows 32 lts remaining, operator fills 33 ltrs - that is fine. But if using some trick, his pump meter showed 40lts then that could mean he was cheating. It hasn't happened yet so I have not really thought what action I could take if such a discrepancy showed up. Its just for my peace of mind I guess.

Check out BHPian comments for more insights and information