Five fuel monitoring and management solutions
for a vehicle fleet
pros and cons of each method

The financial crisis and the COVID-19 pandemic have struck the transportation and logistics industry hard and have caused a huge amount of damage by now. Many companies that own fleets of trucks, light vehicles and special machinery have suffered substantial losses.

In these circumstances, the need to reduce the fuel consumption costs and maintain the efficiency of the business has become one of the paramount requirements for survival. In this article, we will cover the main solutions you could use to achieve this.

vehicles to control fuel consumption at the enterprise

The management and employees of the transport companies, who have been in the business for quite some time by now, are probably well familiar with the current situation. We have already witnessed something similar in 2014-2015 as well as in 2008-2009. Every crisis proves that the GPS monitoring systems are a must in the transportation industry.

On average, the costs related to fuel consumption constitute up to 30-35% of the operating costs of any fleet. In case of a haulage or road-construction company, this number can reach 45-50% mark. Fuel consumption has a direct influence on how profitable a business is. For the latter to work efficiently, the reduction of costs and a comprehensive monitoring effort based on a tight control over the use of fuel are obligatory.

Average cost structure of the vehicle fleet

However, there are still many companies that have yet to implement any fuel monitoring solutions while others need to renovate the already deployed ones. Some managers do not believe this to be that necessary or even turn a blind eye on their employees’ transgressions. Moreover, sometimes a company already has some up-to-date monitoring systems but the management either does not know how to make use of them or simply does not want to do so. In other cases, the implemented solutions are inefficient in certain types of vehicles.

This review will help you get a better grasp of what different ways of fuel monitoring there are and how best to use them. The article will be useful to fleet owners and managers as well as the companies that install telematics equipment.

1. Fuel monitoring without GPS systems

Many companies still run their fleets without any GPS/GLONASS monitoring effort. Let’s assume that the fuel consumption is still under some kind of control and it seems that there is nothing out of ordinary with how fuel is used. Still, can the management be absolutely sure of that? Probably not. An effective monitoring effort implies that you can access the data coming from two or more different sources, compare the numbers and see if there are any discrepancies.

Fuel consumption control by mileage and fuel cards

For instance, here in Russia, the Ministry of Transport provides the average numbers of fuel consumption that can serve as “guidelines” but they are, indeed, “average” and the real numbers can differ from them a great deal.

If you only use the odometer readings, you have to reconcile with the idea that the accuracy of your data may not be as high as desired. The margin of error of these devices can reach up to 15-20% and the drivers can tamper with them to give you “inflated” numbers. If you rely on receipts from gas or diesel stations, there is always a risk of those being falsified.

Fuel cards also cannot be deemed as a reliable way of fuel monitoring: a driver and a gas station employee can always work out some sort of an agreement.

Additionally, no fleet is safe from fuel thefts from the tank, “under-refuelings” and misuse of surpluses. Not to mention the losses while idling, misuse of vehicles for personal benefit by drivers and negligence while operating a unit, which may lead to the waste of gas or diesel. All these are hard to prove or prevent without some extra equipment.

  • Advantages: No
  • Disadvantages: Insufficient data
  • Fuel monitoring efficiency: Low
  • Fuel theft risks: High
  • Application area: Any fleet if every employee is 100% trusted or if the fuel costs are not an issue

2. GPS monitoring without fuel sensors

One of the most commonly known solutions for the monitoring effort is the use of GPS/GLONASS trackers that are able to provide you with the data on the vehicle’s movement, including the coordinates, speed and mileage.

The mileage reported by the trackers is far more accurate than that coming from the odometer. Thus, you gain access to the data that helps calculate the fuel consumption properly.

In addition, you can compare the numbers in both paper reports, filed by the drivers, and the reports on your monitoring platform. This makes it easy to find out if the drivers report “inflated” mileage to cover the fuel thefts.

enterprise fuel consumption control system

The trackers also help analyze the factors that have direct influence on how fuel is used. Thus, you can control if the drivers stick to their itineraries and timetables and if they leave certain geo-zones and do their work diligently without deviating from the set routes and idling without a reason. Many trackers and platforms also give your tools to assess the quality and safety of driving.

However, using only a GPS device does not give you the data on fuel consumption as well as time, place and volume of every refueling, drain or other manipulations.

  • Advantages: Precise basic data on the unit, including the mileage
  • Disadvantages: Lack of means to track fuel manipulations
  • Fuel monitoring efficiency: Low
  • Fuel theft risks: High
  • Application area: Any vehicle fitted with a GPS tracker linked to a monitoring platform

3. Fuel monitoring by means of a CAN bus (standard fuel sensor)

Connecting GPS tracker to CAN bus

What is a CAN bus?

CAN (Controller Area Network) bus is a communication interface that enables interactions between a vehicle’s on-board system and various sensors and other device, both in-built and external. CAN bus is currently present in any modern vehicle.

By connecting a GPS/GLONASS device to the CAN bus of your car or truck via a contactless CAN reader, you gain access to the data on the fuel in the tank collected by the default fuel level sensor and further transmitted to the platform by the tracker. The data from CAN bus also helps keep track of engine hours, pressure, temperature, etc. The only requirement is that the data transmission protocol of the vehicle be an open one.

This is the most easy and cost-efficient way of remote fuel monitoring. Yet the default fuel sensors are not perfect: their margin of error can reach up to 15% of the tank’s total capacity. Therefore, it is still hard to get accurate data on when and where every refueling took place and how much fuel was actually poured into the tank.

The fleet managers that rely only on the CAN bus data may have to be prepared for “dead zones” (5-10% of the tank’s capacity at the bottom and the top), “false” drains or incomprehensive level surges and drops on the platform’s graph chart. Subsequently, the margin of error of fuel level measurement on a vehicle with high fuel consumption can amount to 100 liters.

In addition, you need to remember that this fuel monitoring method is not much of a help when it comes to tracking fuel thefts. Below you can see the fuel graph chart with the data from a vehicle’s default sensor.

fuel level according to the standard sensor

You can compare it with the graph chart showing the data obtained by means of two different sensors installed on the same unit that we provide further below. The red line represents the data from the default sensor. The blue line - the data from an Escort fuel level sensor (see item 5 of the article for more information).

Fuel level graphs via CAN-bus and FLS

Despite its several obvious drawbacks, the CAN bus is your option when it is impossible to mount any external sensors on the vehicle. Besides, not everyone needs 100% accurate data. If you have a fleet of light vehicles and cars, perhaps, it would be easier for you to just fine-tune the reports on the platform, analyze the data from default sensors and still get a pretty good understanding of what is going on with the fuel in the tanks rather than spend money on more expensive equipment that is also fairly difficult to install.

  • Advantages: Easy to install; more data on several extra parameters
  • Disadvantages: High margin of error; difficulty tracking fuel thefts
  • Fuel monitoring efficiency: Medium
  • Fuel theft risks: High
  • Application area: Vehicles with tanks of a complex shape not fit for installation of any extra sensors

4. Flowmeters as means of fuel monitoring

what is fuel flow sensor

How does a flowemeter work?

This sensor needs to be installed on the fuel pipe. It registers how much fuel has gone into the engine and during what time span the engine consumed it.

Some devices of this type can also report on engine hours and fuel temperature.

Flowemeters can boast of a very small margin of error of 1-3%. This helps you get very accurate data on gas consumption and calculate the average numbers for each vehicle in particular. Yet they have their shortcomings too:

  • Expensive: starting with a price tag and finishing with the maintenance costs;
  • Prone to accumulating dirt: every such device needs to be checked and cleaned every now and then, otherwise the whole fuel system could suffer a severe malfunction;
  • Inefficient in tracking drains via the return pipe: you either need another device installed or buy a more expensive flowmeter that can monitor both the injection and return pipes;
  • Useless against the thefts made directly from the tank and “under-refuellings”

Once more, you can check how a floweter and a fuel level sensor perform on the same vehicle. The blue line represents the data collected by the flowemeter. The red line shows the fuel changes registered by the FLS, including every refueling and drain. And the precision difference between the two devices is mere 100ml.

Fuel consumption graph by flow meter and FLS

Despite all these shortcomings, the flowmeters often are the optimal solution for heavy machinery units. First off, the tanks of such vehicles usually have very complex shapes and that makes it difficult to install the capacitive fuel level sensors on them.

Secondly, the high quality flowemeters can also collect the data on motor engines and the overall state of the fuel system which spares you buying and installing several other sensors.

  • Advantages: High precision data on engine hours and extra parameters
  • Disadvantages: High price of the device and high costs of its installation and maintenance; impossible to track fuel thefts from the tank
  • Fuel monitoring efficiency: Medium
  • Fuel theft risks: Medium
  • Application area: Vehicles with tanks of a complex shape not fit for capacitive fuel level sensors

5. Fuel level sensors

installation of fuel level sensors

How do capacitive fuel level sensors work?

The capacitive FLS is installed inside the vehicle’s tanks to keep track of any fuel level changes. In terms of data accuracy, the FLS are no worse than the flowmeters (up to 97-99% of precision).

However, to achieve this level of precision, you need to install and calibrate the sensor properly and then do the tank calibration. Because of that, the installation and configuration should be done by professional integrators.

Just like with any other sensors mentioned above, the FLS needs to be connected to a GPS tracker so that its data could get to the monitoring platform.

If the fuel level in the tank changes, you can then see when and where this happened on the monitoring platform. Moreover, there are sensors that do not require you to use any tracking device with them since they have their own GPS module and GPRS modem.

Along with accurate fuel level data, the capacitive sensors help you:

  • Keep the record of refuelings and drains
  • Track any false refueling or “under-refuelings”
  • Find out about any minute drains
  • Establish if there were any drains via the return pipe

Some people think that the capacitive FLS cannot track the thefts from the return pipe. However, by carefully analyzing the graph charts and reports on the platform, you are very likely to spot such thefts.

fuel level control FLS

The fuel level sensor is a versatile and effective tool for monitoring the gas and diesel consumption on almost any type of vehicle. Yet it also has some disadvantages:

  • The sensor’s tubes can be cut at any length required for a tank unless its height is less than 15 cm because in this case the sensor will not function properly. Therefore, sometimes you cannot install the device on a car or a light vehicle
  • The sensor is difficult to install properly on the tanks of irregular shape. In this case, you either need to install a device of another type or mount two or more sensors on the same tank
  • The margin of error can be higher in the ‘shallow’ tanks of elongated shapes (truck or train tanks) because the fuel in them sloshes whenever the angle of the tank’s inclination changes. In this case, you also need to install two or more sensors. This will increase the costs but you will be able to get accurate data.
  • Advantages: High precision data on fuel level; easy to track any manipulations with fuel
  • Disadvantages: Difficult to install on the tanks of a complex shape
  • Fuel monitoring efficiency: High
  • Fuel theft risks: Low
  • Application area: Any type of vehicle or a stationary tank


As you can see, monitoring gas and diesel consumption efficiently is impossible without proper equipment. Choosing from the solutions suggested above, we would recommend the capacitive FLS. Except for the cases, when a flowmeter or a CAN bus becomes your only option.

Fuel control methods at the enterprise

Still, the capacitive fuel level sensors are a more modern solution with a wider range of functionalities. This is easy to explain: most of the manufacturers of telematics equipment focus on the development and improvement of this type of fuel sensors in particular.

For instance, one of the modern trends is the development of wireless FLS that make use of the BLE (Bluetooth Low Energy) technology. These devices are easier to install since they do not need cables to be connected to a GPS tracker. It is also easy to configure them via a mobile app. All this makes their installation and use more cost-effective and safe: you will not have to worry about the cable damages or wear and tear. And the battery of one sensor can last up to several years before you need to replace it.

To learn more on any caveats of the fuel monitoring and read about real cases of the sensors being implemented - with detailed reports and real numbers - you can visit the blog on our website.