Land Rover Range Rover uses 95 octane gasoline. Currently, there are four grades of gasoline: 89 (formerly 90), 92 (formerly 93), 95 (formerly 97), and 98 (a newly introduced grade). These numbers represent the octane rating of the gasoline, indicating its anti-knock properties, and are unrelated to the cleanliness of the gasoline. It is more scientific and economical to refuel according to the engine's compression ratio or the requirements specified in the user manual, as this allows the engine to operate at its optimal efficiency. During the design phase of an automobile engine, the fuel grade is determined based on the compression ratio. Engine Compression Ratio: The compression ratio is a crucial structural parameter of an engine, representing the ratio of the gas volume when the piston is at the bottom dead center (start of compression) to the gas volume when the piston is at the top dead center (end of compression). From the perspectives of power and fuel economy, a higher compression ratio is generally better. A high compression ratio improves power output and thermal efficiency, enhancing vehicle acceleration and top speed. However, the compression ratio of gasoline engines cannot be excessively high due to limitations in cylinder material performance and the occurrence of combustion knock. High-compression-ratio vehicles require high-octane fuel. The higher the octane rating, the slower the fuel burns, reducing combustion knock and requiring a higher engine compression ratio. Conversely, lower-octane fuel burns faster, increasing combustion knock, and is suitable for engines with lower compression ratios. The octane rating also affects the engine's ignition timing. Lower-octane gasoline burns faster, requiring a retarded ignition angle, while higher-octane fuel burns slower, necessitating an advanced ignition angle.
