How to measure and calculate fuel consumption?


When dashboard reserve lamp is highlighted – reset the trip odometer. Next refuel the car at the petrol station (e.g. V=20 litres) and set out on your way. When the reserve lamp is highlighted again write down the mileage (L) reading displayed by the odometer.

Figure 1. Trip odometer and reset button

Now divide the qty of refilled liters (V) by the mileage (L) and multiply result by 100 to obtain actual fuel consumption Z=V/L *100 [l/100km].


Refill the car totally – until the filling gun pushes off (also service supplied by petrol station staff on request). Reset the trip odometer and set out on your way. When the reserve lamp is highlighted again – refill the car totally (preferably at the same station). Write down mileage reading (L) displayed on the trip odometer and qty of refilled liters (V).

Now divide the qty of refilled liters (V) by the mileage (L) and multiply result by 100 to obtain actual fuel consumption Z=V/L *100 [l/100km].

EXAMPLE (regarding method 1 and 2)

If you made L=300km and used V=20l of fuel, divide 20 by 300 (20/300) and you will obtain (0.0666) and multiply the result by 100.The average fuel consumption is Z=6.6l/100km.

In case of gas powered car it is important to make use of the whole gas and refill the car totally. Next reset the trip odometer and set off on the way. Then following making at least 200km on gas, refill the car totally with gas (at the same petrol station and the same pump). Write down qty of gas (V) and divide it by the mileage (L) – according to odometer reading. Next multiply the result by 100 and you will obtain theaverage gas consumption (Z).

Note: during refilling the shut off fuel gun shall be in good order.


If you know that there are remains of gas inside the tank – pull up at the petrol station and refuel the car totally. Next reset the odometer and set off on the way. If during refilling it is evident that you filled e.g. V=22l of gas and the trip odometer reading is L=240 km, divide 22 by 240 (22/240) and the result will be (0.092). Next multiply the result by 100. Your average gas consumption is Z=9.2l /100km.


How to reduce fuel consumption and increase/improve gas mileage?



Keeping your vehicle in good shape can help with its fuel efficiency. Even simple things like dirty air filters, excessive exhaust emissions, and underinflated tires can combine to reduce fuel economy.

Most common defects that have negative impact on fuel economy include:

  • Faulty brake system – e.g. seized cylinders;
  • Improper toe-in and steering geometry;
  • Excessively tightened wheel bearings;
  • Dirty air filter;
  • Faulty ignition system (e.g. worn plugs, faulty timer-distributor, worn HV cables);
  • Damaged thermostat;
  • Improper valve timing, ignition;
  • Leakage of exhaust system;
  • Protruding body parts (e.g. lose cover under the engine, protruding bumper, etc.);
  • Worn parts subjected to friction (piston rings and cylinder liners).

If tyres wear does not follow evenly, squeal on bends or the car is turning sideways, it is probably necessary to correct steering geometry (in particular toe-in). To check it, jack up a car and turn wheels manually. In case of any irregular rotation check the brake system and bearings (tightening moment).

Fuel mixture combustion will not follow properly, if plugs and ignition cables are faulty. Similar fuel losses follow as a result of a faulty time- distributor and clogged air filter.

Other defect that has a significant impact on fuel economy is a faulty thermostat (slow heating of the engine and low temperature of the engine), as well as leakages of exhaust system (usually indicated with noisy operation and smell of exhaust fumes).

Excessive fuel consumption follows as a result of engine wear also.

In case of a few years car you may expect significant wear of piston rings and cylinder bearing surfaces. This result in cylinder lower compression pressure compared to the nominal parameters. Lower compression pressure and uneven cylinder pressure is one of major causes resulting in excessive fuel consumption. Ceramizer - engine additive in most cases increases and level compression pressure up to the nominal value, and at the same time provides for regeneration of engine parts and consequently fuel consumption reduction.

It is worthwhile to diagnose the engine and measure compression pressure before and after application of Ceramizer.

Fig. 2. Reference compression pressure before and after application of Ceramizer - engine additive


Another factor significant for fuel consumption is a car mass. The bigger weight of the car, the more power is required (obtained from fuel combustion) to set it in motion – and consequently more fuel will be consumed. In general the rule is that each extra 100kg in case of city traffic results in increase of fuel consumption by around 0.6l.

Would you like to decrease fuel consumption? Keep the car as light as reasonably possible. For each 100 pounds of extra weight, gas mileage is reduced by as much as 4 percent. Limit the everyday items in your trunk or cargo area to the bare necessities, which should include some emergency items. Don't haul around what you won't be using. How about replacing the spare wheel with the light emergency wheel. You can also remove the spare wheel (not recommended), jack, and wheel spanner for the sake of a sealing preparation (available in any car accessories shop). Also some wheels make for car mass increase and poor fuel economy, e.g. 15” rim set along with tyres weighs around 70kg?

It makes for so called unsprung mass.

The bigger weight of your wheels (rims and tyres) the bigger will fuel consumption and slower acceleration and less efficient and comfortable suspension system performance be (heavy wheels on a bumpy surface make for extra operation of the suspension system).

Is it possible to reduce fuel consumption? Check wheels of your car and follow all tips of car manufacturer. Do not use bigger wheels than recommended.


When replacing factory made 174/70 R14 wheels with 205/50 R16 ones, the weight of the car will increase in total by over 15kg. It is assumed that extra mass of wheels results in load 4 times as much as in real. In this case extra 15kg on wheels result in extra 60kg regarding of car total weight. How is it possible? Simply wheels not only make for additional load of the vehicle but provide drive transmission also (rotating kinetic energy is required).

It is said that aluminium wheel rims are light, while actually most often they are heavier than steel ones. Although it is true that aluminium density is smaller almost 3 times as much as in case of steel (consequently aluminium weighs less), yet to ensure required strength of aluminium rims, some heavy metal alloys are used. Furthermore the aluminium rim itself is thicker compared to the steel one. Just check and compare thickness of the aluminium alloy rim and the steel one.

If you opt for aluminium wheels select those which are both light and strong. If you know wheel rim manufacturer and preferred model, check its weight, e.g. on the following website: It the given wheel is not listed on the website, consult its weight with a manufacturer or vendor.


Speaking about wheels it is worthwhile to have a look at tyres. The key aspect is rolling resistance that depends on:

  • Tyres inflation;
  • Tyre width;
  • Tyre tread;
  • Tyre type and road conditions.

How do tyres enable to reduce fuel consumption?

The most crucial factor for fuel consumption that is both free of charge and very easy to control is tyre pressure.

Periodic checks (once a month) and maintaining properly inflated tyres is critical to fuel economy and to safety. The recommended tire pressure is displayed in your vehicle, typically on a sticker inside the glove box door or on one of the doorposts. It's also in your owner's manual (remember to keep proper inflation that is different in case of front and rear wheels).

Underinflated tyres cause vehicle drag and increase fuel consumption by several percent. They also compromise handling ability in turns and in emergency manoeuvres.

Always check pressure when tyres are cold. Remember that before setting out on the way with totally loaded car it is recommended to increase pressure, in particular of rear tyres (The recommended tire pressure is displayed in your service manual, or typically on a sticker inside the glove box door or on one of the doorposts).

Figure 3. Reference table with data concerning tyre type and pressure

Observe tyre width recommended by the manufacturer. The wider tyres, the bigger friction and increased fuel consumption. Replacement of 175 wide tyres with 195 ones may result in increase of fuel consumption by 0.5-0.7l per 100km. Match the tire size as listed on the tire sidewall with that on the sticker or in the owner's manual. Remember that proper tyres make the car holds the road. Proper wheels are able to work with your vehicle's suspension to provide maximum handling, steering, and braking ability.

Winter tyres shall be used if temperature drops below +7oC. These tyres feature with bigger rolling resistance due to rubber mixture used for manufacturing and the specific pitch pattern.

Remember to remove winter tyres immediately after winter season.

Tyre manufacturers improve continually their products, in particular the tread. Tyres with the tread that causes minimum resistance are called eco-tyres and there is not much potential for fuel economy improvement. For example TUV tests of Goodyear Efficient Grip tyres confirmed fuel consumption reduction by 1.9 %.


Aerodynamic resistance is another factor that has impact on fuel economy. Each part protruding out of the body generates significant aerodynamic resistance (e.g. loose cover under the engine, protruding bumper, etc.) In particular it is important in case of high speeds and long journeys.

When driving with bicycles fixed on the roof rack or with so called box, fuel consumption increase may follow by up to a few litres.

If you travel with the roof rack or box, drive slowly to decrease aerodynamic resistance and reduce fuel consumption (the bigger speed the more aerodynamic resistance that follows not linearly, but by square).

Aerodynamic resistance is bigger also, if car windows are open (by about 5%), sunroof is open (by about 10%) and in case of removed hub covers (by several %). All these factors make for increase of fuel consumption. When traveling with speed over 60 km/h remember to close all windows and use an air supply blower instead. For example in case of the car having average aerodynamic properties, during travelling with speed up to 85km/h, the aerodynamic resistance is not significant with regard to the total used power and only 9 HP is required to overcome it. But when travelling with speed of 120 km/h, 25 HP is required to overcome aerodynamic resistance, and in case of 150 km/h as many as 54 HP is required to overcome aerodynamic resistance, what will costs you when pumping fuel.


Passenger vehicle of 150 HP and power required to overcome aerodynamic resistance at different speeds.

Speed km/h 68 85 102 119 136 153 170 187 200 221
Power required to overcome aerodynamic resistance KM 5 9 15 25 38 54 74 98 128 162


Some fuel savings are also possible thanks to limited use of power receivers as air-conditioning, heated rear window or heated wing mirrors.

It is recommended e.g. to switch off the heated rear window, if the rear window is clear already after making a few km in the morning.

It also the similar in case of air-conditioning that makes for significant increase of fuel consumption, namely by about up to 10%. If you travel with open windows or sun-roof with air-conditioning switched on, you waste a lot of fuel.

Remember to close windows or sun-roof or both of them, as when open they contradict operation of air-conditioning and increases in addition aerodynamic resistance.


Use of adequate gearbox and engine lubricating oils decreases friction and fuel consumption. Ceramizer when added to the oil generates slippery and hard ceramic-metal coating, and at the same time reduces friction what results in improved performance and efficiency of engine parts. And reduced friction improves fuel economy. Furthermore by applying Ceramizer, you provide for regeneration and protection of engine parts against wear, what in the long run results in additional savings (long life of engine, gearbox, rear axle, power steering).

Note to refuel the car (petrol, diesel oil or gas) at reputed petrol stations. Fuel of poor quality usually features with low octane rating, which may result in knocking very dangerous for the engine and fuel-air mixture inefficient combustion. Damage of engine may follow after making a few/several thousand of km on this fuel.

By adding Ceramizer - fuel additive to fuel or diesel oil, you can minimize the risk of damaging the engine by poor quality fuel. In addition this additive improves operation of the fuelling system (clean injection, combustion chamber, valve heads).

When refuelling the car fill the tank as much as possible to avoid water condensation inside the tank. Refuelling with a small qty makes it necessary to visit other stations, sometimes remotely located. It may also happen that may you will be forced to visit the petrol station only to refuel the car, what does not promote fuel economy at all.

Check, if in your area there are any self-service petrol stations (e.g. Neste branded), as usually they offer petrol lower prices comparing to other stations. Refuelling at such petrol station is very easy: you just need to put the banknote into the machine and select the pump and next you start filling up the tank. The machine will automatically stop the pump. Note that this machine does not return the change. You can make payment by the credit card also.



Watch the engine speed, as well as road speed. This allows you to find the engine's most efficient rpm and stay close to that point whenever feasible. Sometimes rpm is marked on rev. counter with green colour, but in case of the car with the computer, it is possible to determine rpm on the basis of computer reading with regards to actual fuel consumption. In other case it is worth to make some searching in the Internet and find information on the given engine power and torque (sometimes specified also in the technical documentation or car manual provided by car manufacturer). This way you may find out engine rpm that promotes fuel economy.

It might be surprising but in general economical engine rpm may not be the lowest one. That is why it is recommended not to shift into upper gears immediately, if possible, as it may have negative impact on engine wear, in particular connecting –rod bearing set and it may pose a risk when accelerating is desired.

The lowest fuel consumption is obtained near the max. torque, and rpm where intersection of power and torque curves follows. The below example specifies how to determine the rpm that promotes fuel economy on the basis of power and torque.


Determine rpm. range that ensures optimal low fuel consumption on the basis of engine power and torque diagram (it is possible by searching with Google Images browser by entering: engine type and model along with "dyno chart" or "brake stand" term).

The most efficient rpm is near the highest torque and is limited on the diagram with the intersection of the torque and power.

Figure. 4. Determination of engine rpm ensuring low fuel consumption.


Accelerate no more forcefully than needed to mesh smoothly into traffic. Avoid case of alternate dynamic acceleration and sudden braking. The best drivers are smooth and efficient in every move they make.

In fact dynamic acceleration and sudden braking results in poor economy in particular in case of city traffic where it is very evident on two line road. Very often cars on the slower line move slowly but smoothly comparing to the other line for those in hurry. Those who use very often acceleration pedal in fact have to use brake pedal also. In addition to increased fuel consumption also significant wear of brake blocks follows as well as increased risk of collision. Actually drivers very rarely reach their destination before others. So try to maintain steady speed and drive smoothly.

In case of very congested roads simply pull out and shift into idle gear, so that the car rolls slowly. Observe carefully and try to anticipate road conditions to avoid sudden braking and accelerating. Even jabbing the accelerator during passing maneuvers or lane changes eats away at fuel economy. When on the highway, zooming up to the traffic ahead, then having to hit your brakes is another fuel-wasting exercise.


We tend to allow our emotions to affect our driving. Whenever you are elated or angry, calm down before getting behind the wheel.

Emotionally intense drivers are a lot more likely to engage in fuel-wasting (and dangerous) acts: gunning the engine, spinning the wheels, and worse. Try to be a kind driver to the benefit of all road users.


If possible use the engine to slow the car down. Engine braking is usually done by downshifting the vehicle to a lower gear then it typically would be in (e.g. 4 to 3, 3 to 2 etc.) During engine braking injections stand still what reduces fuel consumption compared to the traditional braking (slowing down the car with the brake pedal only). In this case the engine is driven with the kinematic energy of the car and the controller does not feed fuel. Fuel feeding is provided at around 1000 rpm – to keep the engine operating. Consequently when using engine braking shift to lower gear when engine drops to around 1200 rpm.

Engine braking is very essential when driving in mountains. It saves brake blocks and prevents their overheating. Brake system overheating (brake fluid boiling or brake block overheating) may be detrimental to braking efficiency.

Engine braking does not reduce fuel consumption in case of the engine with the old type carburetor or gas (mixer). In this case it is recommended to shift into idle gear before reaching the cross-roads.


Make use of GPS navigation and tune into local radio, CB radio for up-to-the-minute reports on traffic conditions and accidents. Staying tuned is most vital in bad weather. It also enables to plan the optimal journey. This way you will conserve fuel normally used when in traffic jam.

Usually radio news specify where exactly road impediments may be expected – kilometers posts are usually at road’s shoulder. Sometimes GPS navigation is very handy as it may direct you to avoid traffic jam.


Do not heat up the engine when stopped. The best economy is ensured when heating up the cold engine during traveling. Pull away immediately after engine switching on.


Accelerate no more forcefully than needed to mesh smoothly into traffic. Racing up to cruising speed may later drain your wallet. Note very often pushing pressing the pedal at 3/4 and 4/4 (maximum) ensures the same effects.


Close windows – make use of the air supply blower. Traveling at speed of 100 km/h with open windows increases fuel consumption by around 5%. On the other hand travelling with the open sunroof increases fuel consumption by around 10%.


Shut off the engine when at stop longer than 30-60 seconds. A minute of idling, however, consumes more fuel than a restart.


Adherence to eco-driving rules as well as keeping the car in good shape and maintenance are the key factors for fuel economy.

You may improve it even more and decrease fuel consumption by applying Ceramizer, namely an additive (an oil additive) providing for engine parts regeneration.

Such good results are possible because of 2 main reasons:

  1. Ceramizer provides hard and slippery protecting metal-ceramic coating on the surface that reduces friction of working parts.
  2. Ceramizer regenerates parts. Following application and mixing with the engine oil this additive increases and level cylinder compression pressure. Proper and low fuel combustion is ensured exclusively in case of the engine having high and level compression pressure.

Figure. 7. Regeneration after applying the oil with Ceramizer