To increase fuel efficiency, there are a limited number of options. While there are a plethora of product marketers who claim theirs will increase fuel efficiency, it is not true. Even if marketers do not claim a product will increase fuel economy overtly, it is often insinuated that a product can do so with the use of subtle and ambiguous language.

Increasing fuel economy by small incremental amounts notwithstanding, there are only a few products proven to extend the mileage (or hours) of a tank of fuel. It is true that some products increase fuel mileage by making an engine run more efficiently, but the increase in mileage is typically almost immeasurable.

There is a difference between an engine operating efficiently and increasing the efficiency of a fuel.

It is possible to change the octane rating of a fuel. Cleaning the internal combustion components of an engine is another option. Adding internal combustion component lubricants all increase the efficiency at which an engine runs is a possibility. However, these measures do not increase fuel efficiency, at least not a noticeable amount.

To increase fuel efficiency, it is necessary to increase the fuel density of a fuel or to increase the efficiency at which a fuel burns. Incomplete fuel burn is a major factor in poor fuel economy. The other — and the simplest — means of increasing fuel economy is driving more efficiently.

Ways of Increasing Fuel Efficiency While Driving

How a vehicle or machine is driven impacts the rate at which fuel burns more than anything else. More than even the fuel density of diesel, gasoline, natural gas, or biofuel, driving determines “gas” mileage. Even expert drivers with decades of experience who have the ability to drive without stressing an engine do not always understand how their driving impacts fuel economy.

RPM Versus Speed

There is no correlation between the speed at which a person drives and the rate at which fuel burns. Theoretically, it is possible to burn less fuel going 60 miles per hour than driving 10 miles per hour. The revolutions per minute (rpm) of an engine is the factor which most greatly impacts the rate at which a fuel burns. The tenant is simple, the higher the RPM, the more fuel an engine burns.

It may seem obvious, but it is worth repeating, revving an engine wastes fuel. “You should be in the highest practical gear at the lowest possible cruising speed.” Interestingly, there is almost a direct correlation between the amount of fuel an engine burns and rpm. Double the rpm and the engine burns roughly twice the amount of fuel.

In other words, if a vehicle gets 55 miles per gallon at 2,000 RPM, it will get around 25 miles per gallon at 5,000 rpm.

Other Means of Reducing Fuel Consumption While Driving a Vehicle or Operating a Machine

Increase fuel efficiency by reducing idle time. Idle time is another waste of fuel, a massive waste. By limiting idle time, a driver or operator can decrease fuel consumption dramatically. Fuel used as an engine runs while a piece of heavy equipment sits idle constitutes a staggering percentage of the fuel a machine uses per day according to the heavy equipment manufacturer CAT.

“Some industry experts say it’s not unusual for idle time to represent as much as 40-50% of the total running time.”

Idle time is an equally large factor with respect to dump and fleet trucks. Idle time can be up to 35 percent of fuel costs according to an article published in the National Academic Press. Clearly, idle time has a huge influence on semis, dump trucks, and transportation vehicles (buses).

But, rpm is still the biggest factor.

By maintaining rpm at a low rate on a regular basis and attempting to eliminate idle-time fuel consumption, drivers and operators can save significant sums of fuel, hence, money.

What Role Cetane/Octane Play in Fuel Efficiency

There is a misconception that cetane/octane ratings increase fuel efficiency in a positive manner. Cetane/octane, if anything, reduces the efficiency of a fuel. The reason is simple: cetane/octane supplementation is the effect of adding solvents to fuel. Solvents — typically made from fossil fuel or biofuel byproducts — have lower fuel densities than diesel and petroleum.

Energy Density and Fuels: Why Solvents — Cetane/Octane Boosters — Lower Fuel Economy

The lower the energy density of a fuel, the less energy that fuel produces. Cetane/octane rating is not a farce, however. Cetane/octane rating serves an important purpose. Cetane/octane rating is a measure of how much pressure a fuel can resist before combusting.

If gasoline combusts as a result of pressure rather than exposure to a spark, the effect is called a “prefire.” If an engine pre-fires, the pressure combustion of gasoline causes knocking and pings. By raising the octane rating of gasoline with a treatment or additive, the amount of pressure required to create compression combustion increases.

That means the fuel will begin to combust as a result exposure to a spark rather than compression and pings and knocking disappear.

All diesel engines, on the other hand, are compression engines. Diesel engines combust diesel fuel with compression rather than a spark. Nevertheless, there is an optimum level of pressure at which diesel combusts. If diesel combusts early — under less pressure — potential energy in the diesel is lost. By adding a cetane supplement, drivers and operators can increase the amount of pressure required to combust diesel which in turn increases the energy efficiency of the fuel.

Cetane/Octane Rating Not Equivalent to Fuel Density

But, just because more pressure is necessary to combust a fuel does not mean that fuel has a higher fuel density. In fact, higher cetane/octane fuels have a lower fuel density than unsupplemented fuel. In other words, while high cetane/octane fuels make an engine run more smoothly, they reduce the amount of energy a fuel produces.

That is because the energy density of cetane/octane boosters have a lower fuel density than the fuels they supplement. So again, while important, cetane/octane boosters do not increase the economy of a fuel.

What Fuel Types are Most Fuel Efficient

With respect to vehicles, trucks, and heavy machinery, diesel is the most fuel-efficient fossil fuel. Fuel oil has an even greater fuel density than diesel, but it is extremely difficult to combust. While that makes it very safe to use for in-home heating and industrial furnaces and boilers, fuel oil is impractical for spark and compression engines.

With respect to energy per unit of measure, after diesel is petroleum. Relative to diesel and petroleum, biofuels and natural gas have relatively low fuel densities.

The higher the energy density — fuel density — the more efficient a fuel. Diesel has an energy density of 36.8 megajoules per liter. Gasoline has an energy density of 34.2. Natural gas has an energy density of 22.2.

Fuel Efficiency of Biofuels

Biofuels may or may not decrease emissions. While the combustion emissions of biofuel are less than that of fuel oil, diesel, and petroleum, the overall carbon footprint of biofuels may actually be more than that of fossil fuels, considerably more.

The overall emissions produced by biofuels is a controversial debate. The fuel efficiency — the fuel density of biofuels, — on the other hand, is not. Biofuels have low fuel densities in relation to fossil fuels.

Biodiesel, for example, has a fuel density of _____. That is ___% lower than that of diesel and ____% lower than that of gasoline. And, the cost of biofuels is higher than that of diesel and petroleum. Not only do biofuels provide less energy per unit of measure, every liter/gallon is more expensive.

Converting to biofuels is not a means of increasing fuel economy.

Do Additives/Treatments Improve Fuel Efficiency?

Fuel additives and treatments do not increase fuel efficiency. Additives and treatments improve engine efficiency by increasing cetane/octane, by removing hydrocarbon buildup, or by lubricating the internal combustion parts of an engine. To a small degree, fuel additives and treatments can increase fuel efficiency by improving the efficiency of an engine.

But, the reduction of fuel density negates any gains in engine efficiency produced by an increase in engine efficiency.

Almost all additives and treatments are solvents. Byproducts of fossil fuel refining, additive/treatment solvents have lower energy densities than do diesel and gasoline. So, by supplementing fuel with detergents, cetane/octane boosters, and lubricants, drivers and operators reduce the economy of a fuel.

Do Catalytic Converters Improve Fuel Efficiency?

Catalytic converters do not improve fuel economy. The purpose of a catalytic converter is to reduce emissions. A catalytic converter plays no role in the combustion of fuel nor fuel density. A catalytic is a post-combustion mechanical device made of noble metals.

No engine combusts fossil fuels completely. A portion of all fuels escapes out through the exhaust unburned. The purpose of a catalytic converter is to burn up fuel that fails to combust in the engine. In no way, positively or negatively, does a catalytic converter affect a vehicle’s or machine’s fuel efficiency.

Does a Turbo Increase Fuel Efficiency?

A turbo does not increase fuel efficiency. It is far more likely a turbo will reduce fuel economy. Turbos are complex mechanisms that increase power with a simple concept: add more oxygen to a fuel mixture. It is the addition of oxygen to a fuel mixture that decreases fuel efficiency.

There is a precise and necessary fuel-to-oxygen ratio for every engine called the stoichiometric ratio. Without the correct stoichiometric mixture, an engine has problems.

If the mixture has too much fuel and not enough oxygen, the result is a “rich” mix. A rich mix leads to excessive unburned fuel. A rich mix means unburned fuel is lost out the exhaust. A “lean” mix — excessive amounts of oxygen — leads to pre-firing. Again, pre-firing leads to pinging, knocking, and overheating.

The stoichiometric ratio of an engine prevents both rich and lean mixes. So, when a turbo blows extra oxygen into a combustion chamber, the engine must counteract the excessive oxygen with more fuel. “In response, the fuel system shoots in plenty of extra fuel – and there go your fuel savings.”

Aftermarket Devices and Products that Increase Fuel Economy

To increase fuel efficiency, an aftermarket device or product is typically necessary if a vehicle, truck, or machine is being operated at low rpm. As additives, treatments, catalytic converters, and turbos do not increase fuel economy, another device is necessary.

A fuel catalyst is that device.

How Do Fuel Catalysts Improve Fuel Efficiency and How?

A fuel catalyst increases fuel efficiency by increasing the combustion efficiency of a fuel. There is one universal with respect to fuel combustion: oxygen. A sufficient sum of oxygen mixed in with a fuel is required. Equally as important, the fuel molecules must oxygenate.

Fossil fuels are heterogeneous mixtures. They are neither uniform nor is every fuel molecule prepared for oxygenation. For a fuel molecule to oxygenize, exposure of the surface of the fuel molecule is necessary. Fossil fuel molecules clump together in clusters which prevents surface area exposure of the molecules inside the cluster.

Polarization is the reason fuel molecules cluster together.

A fuel catalyst is a mechanical device that mounts on a fuel line. It is a pre-combustion mechanism through which fuel travels prior to entering the combustion chamber of an engine. Inside a fuel catalyst are noble metals — typically the same noble metals found in a catalytic converter.

When fuel travels through a fuel catalyst, the noble metals inside the catalyst cylinder neutralize the charge of the fuel molecules clustered together. No longer polarized, the fuel molecules drift apart. Separated, the fuel molecules have greater surface area and are available for oxygenation.

While there may be other fuel saving devices that can increase fuel efficiency, only fuel catalysts have the science and track record to guarantee savings.