1. Energy Density: Petrol has a higher energy density compared to coal or natural gas. This means that it can store more energy per unit volume, making it more efficient for transportation purposes. Petrol contains around 34.2 megajoules (MJ) of energy per liter, while coal contains around 24 MJ/kg and natural gas contains around 38.6 MJ/m³.
2. Ease of Use: Petrol is a liquid fuel, which makes it easier to handle, transport, and store compared to coal or natural gas. It can be easily pumped and injected into engines, whereas coal and natural gas require specialized equipment and infrastructure for handling.
3. Combustion Characteristics: Petrol has better combustion characteristics compared to coal or natural gas. It burns relatively cleanly and produces less soot and pollutants. Coal, on the other hand, produces significant amounts of ash, sulfur dioxide, and other pollutants when burned. Natural gas burns cleaner than coal but still requires specialized combustion systems.
4. Infrastructure: The infrastructure for petrol-powered vehicles is well-established and widely available. There are numerous petrol stations and fueling facilities across the world, making it convenient to refuel vehicles. In contrast, the infrastructure for coal or natural gas-powered vehicles is limited and requires significant investment to develop.
5. Engine Efficiency: Petrol engines are generally more efficient than coal or natural gas engines. They can convert a higher percentage of the fuel's energy into mechanical work, resulting in better fuel economy and performance.
6. Emissions Control: Petrol engines can be equipped with various emissions control systems, such as catalytic converters, to reduce harmful emissions. This helps in meeting environmental regulations and improving air quality.
While coal and natural gas have been used in some specialized vehicles, such as coal-fired steam engines and natural gas-powered vehicles, petrol remains the dominant fuel choice for cars due to its energy density, ease of use, combustion characteristics, established infrastructure, engine efficiency, and emissions control capabilities.
