Which fuel is the most efficient?

Gasoline is a typical example of fuel. It is a liquid fossil fuel refined and processed from petroleum, with hydrocarbons as its main component. As a common fuel for internal combustion engines, gasoline is widely used in vehicles such as cars, motorcycles, small aircraft, and some mechanical equipment. It releases chemical energy through combustion and converts it into mechanical energy to provide power. Based on octane ratings, gasoline can be classified into different grades to suit engines with varying compression ratios, such as the common 92-octane and 95-octane gasoline. Furthermore, gasoline belongs to the category of fuel oil, which is a subclass of fuel and includes various types such as gasoline, diesel, and kerosene. All of them release energy through combustion to meet diverse power needs.

The fuel types for Class 8 vehicles mainly include diesel, natural gas, and hybrid electric power, among others. Among these, diesel fuel dominates, accounting for over 75% of the market share in this category in 2024. This is because it provides strong power, reliability, and meets the demands of high-intensity industries such as long-haul freight and construction, supported by an extensive refueling infrastructure. Hybrid electric options are also developing gradually; for instance, the hybrid system retrofit design introduced in January 2025 combines batteries with diesel generators to deliver high horsepower, substantial torque output, and extended driving range. Natural gas is another available fuel option for this vehicle category. These fuel types each have distinct features: diesel maintains its mainstream position due to proven maturity and practicality, while cleaner alternatives like hybrid electric power are being progressively adopted to align with the industry's pursuit of more sustainable transportation solutions.

In Malaysia, the efficiency of fuel types must be evaluated based on specific application scenarios. For household passenger vehicles, hybrids (combining gasoline and electric power) offer an efficient solution: pure electric operation in urban areas reduces fuel consumption, while reliance on internal combustion engines for long-distance travel eliminates range anxiety, making them well-suited for both local congested conditions and extended journeys. Among conventional fuel vehicles, RON95 gasoline stands out as a cost-effective and efficient option due to government subsidies and excellent engine compatibility (e.g., turbocharged engines in certain models are calibrated to fully exploit its anti-knock properties), delivering both performance and fuel economy. In heavy transport, hydrogen-powered vehicles—with rapid refueling, extended range, and zero emissions—along with biodiesel (such as airport-tested B20) that reduces fossil fuel dependence, represent efficient and eco-friendly alternatives. Methanol fuel, as a clean energy source, enhances energy utilization efficiency while curbing harmful emissions, positioning it as a promising future fuel option. Although electric vehicles boast low maintenance costs and zero emissions, their current limitations—inadequate charging infrastructure and higher upfront costs—render them less practical and efficient compared to hybrids or RON95-powered vehicles.

In the current fuel pricing system, RON95 petrol is the cheapest type of fuel. Malaysian citizens can enjoy a subsidized price of RM1.99 per liter upon presenting their national identity card. This price applies to the BUDI MADANI RON95 Subsidy Scheme, with a monthly subsidy limit of 300 liters per person. Non-citizens and foreign-registered vehicles are not eligible for this subsidy and must purchase fuel at market prices. Among these, the price of RON95 for non-citizens, after a recent adjustment, is approximately RM2.62 per liter, while the price of RON97 petrol is about RM3.27 per liter, and the price of diesel such as EURO5 B10 is around RM3.06 per liter—all higher than the subsidized RON95 price available to citizens. For most drivers, RON95 petrol is sufficient to meet the engine requirements of daily vehicles, combining economy and applicability, and is a fuel option with outstanding cost-effectiveness in the local market.

There are various types of gases used as fuels, commonly including natural gas (primarily composed of methane), liquefied petroleum gas (LPG, mainly containing propane and butane), hydrogen, coal gas (a mixture of carbon monoxide and hydrogen), and biogas. These gaseous fuels are considered clean energy sources due to their complete combustion and low emission pollution. In the automotive sector, the primary gaseous fuels used are compressed natural gas (CNG), liquefied natural gas (LNG), and liquefied petroleum gas (LPG). LNG is produced by cooling natural gas to -161.5°C for liquefaction and storage, offering high energy density and being suitable for long-haul commercial vehicles. CNG is natural gas stored in a compressed gaseous state, with refueling stations being relatively widespread, making it commonly used in taxis and urban buses. LPG, a byproduct of petroleum refining, is easily liquefied and stored, and is also utilized in certain light-duty vehicles. The use of these gaseous fuels contributes to reduced vehicle emissions and extended engine lifespan, garnering significant attention in the context of energy scarcity.

E85 fuel is a type of flex-fuel, mainly composed of a mixture of ethanol and gasoline, with the ethanol content reaching up to 85% and gasoline accounting for 15%. In practical applications, the proportion of ethanol may fluctuate between 51% and 83% due to factors such as geographical location and season. It is suitable for flexible fuel vehicles (FFVs), whose electronic management systems can automatically adjust operating parameters according to the actual proportion of fuel in the tank to ensure that vehicle performance is not affected. As a fuel type related to renewable energy, E85 plays a transitional role in the energy transition process. It can not only reduce dependence on traditional fossil fuels but also adapt to some existing transportation infrastructure, providing a flexible option for the transition from traditional fuels to cleaner energy sources.

In the local area, the main types of fuel commonly used for cars are two kinds of unleaded gasoline: RON95 and RON97. RON95 is the most popular and economical choice, with an affordable price and wide availability. It can meet the daily driving needs of most ordinary models (such as the 2019 Kia Cerato and 2020 Volkswagen Passat). It complies with the MS228 national fuel standard, and the cleaning additives it contains can effectively maintain the cleanliness of the fuel injection system and combustion chamber. RON97 has a higher octane rating, making it suitable for high-performance models or use under high-load conditions. It optimizes the engine's anti-knock performance, and occasional use can also deliver smoother power output, but its cost is significantly higher than RON95. All local gasoline must meet EURO 4M or higher standards, eliminating the need for additional fuel additives. Furthermore, due to the floating fuel price mechanism, the prices of both gasoline types fluctuate with market conditions, allowing car owners to select the appropriate fuel based on vehicle requirements and usage needs.

RPM (Revolutions Per Minute) and horsepower are not the same concept. RPM refers to the number of rotations an engine makes per minute and is a unit for measuring engine speed; horsepower (HP), on the other hand, is a unit of power for measuring an engine's work capacity. The two are closely related. The calculation of horsepower requires combining torque and RPM, for example, using the formula: horsepower = torque × RPM ÷ 5252 (imperial conversion) or ÷ 9549 (metric conversion). Higher RPM generally enables an engine to produce more horsepower, but the actual output also depends on parameters such as torque, and the engine's horsepower performance varies across different RPM ranges.

The rotation speed of a 0.5 hp motor is not a fixed value; it depends on the motor type, number of pole pairs, and application scenario. In AC asynchronous motors commonly used in Malaysia, the rotation speed is closely related to the power supply frequency and the number of pole pairs. Malaysia's power supply frequency is 50 Hz, and the synchronous speed is calculated by the formula n = 60f/p (where f is the frequency and p is the number of pole pairs). For example, the synchronous speed of a 2-pole asynchronous motor is 3000 rpm, and the actual operating speed is slightly lower due to the slip, approximately 2800-2900 rpm; the synchronous speed of a 4-pole motor is 1500 rpm, with an actual speed of about 1400-1450 rpm; and a 6-pole motor has a synchronous speed of 1000 rpm, with an actual speed of around 950-980 rpm. In the Malaysian market, 0.5 hp motors are widely used in small household water pumps, fans, or small industrial equipment. Different brands (including local brands and models sold in Malaysia by international brands) offer products with different numbers of pole pairs according to requirements. Users need to choose based on the application: for high-speed requirements (such as some ventilation fans), 2-pole motors can be selected; for medium-speed and high-torque requirements (such as small water supply pumps), 4-pole motors are suitable; and for low-speed and high-torque scenarios, 6-pole motors can be chosen. When purchasing, users can confirm whether the rated speed marked on the motor nameplate matches the specific usage requirements.

The calculation method of motor speed varies depending on the type of motor. For synchronous motors, their speed is directly related to the power supply frequency and the number of pole pairs, with the calculation formula being n = (60×f)/p, where n represents the speed (in rpm, i.e., revolutions per minute), f is the power supply frequency (in Hz), and p is the number of pole pairs of the motor (the number of pole pairs is equal to the number of poles divided by 2). The actual speed of an asynchronous motor is lower than the synchronous speed, so the slip ratio needs to be introduced for calculation, with the formula n = (60×f/p)×(1 - s), where s is the slip ratio (usually expressed as a decimal, generally between 0.01 and 0.05 at full load). The speed calculation formula for a DC motor is n = (U - Iₐ×Rₐ)/(Cₑ×Φ), where U is the armature voltage, Iₐ is the armature current, Rₐ is the armature circuit resistance, Cₑ is the motor constant, and Φ is the flux per pole. For example, if the power supply frequency is 50 Hz and the number of pole pairs is 2, the speed of the synchronous motor is 60×50÷2 = 1500 rpm; if it is an asynchronous motor with a slip ratio of 0.03, the actual speed is 1500×(1 - 0.03) = 1455 rpm. Mastering these calculation formulas helps to understand the working principle of motors, evaluate their performance and energy consumption, thereby selecting and applying motors more reasonably.