Luxury cars use 95 octane gasoline to prevent engine knocking. 95 octane gasoline has strong anti-knock properties and will not ignite under high pressure, ensuring the engine operates at the optimal ignition timing without affecting power output. The specific reasons are as follows: Gasoline is fundamentally related to the engine's compression ratio. Higher compression ratios result in greater power and efficiency but lower stability, necessitating gasoline with high anti-knock properties. Using 95 octane gasoline enhances performance. It has a higher octane rating than 92 octane gasoline, improving low-speed performance in gasoline engines. 95 octane gasoline ensures engine stability. Higher-octane gasoline is more stable. If a car designed for 95 octane uses 92 octane, it may lead to increased fuel consumption, reduced power, and even trigger the engine warning light in severe cases. Besides checking the recommended gasoline grade in the car's manual, you can also find it on the fuel cap. Typically, the gasoline grade can be determined by the engine's compression ratio: cars with a compression ratio between 8.6-9.9 should use 92 octane, those between 10.0-11.5 should use 95 octane, and higher compression ratios require 98 octane. However, with modern technologies, compression ratio alone may not dictate the gasoline grade, as factors like ignition timing, turbocharging, and Atkinson cycle technology also play a role. Generally, higher-octane gasoline has a higher octane rating and better anti-knock properties. 92 octane gasoline contains 92% isooctane and 8% n-heptane, while 95 octane gasoline contains 95% isooctane and 5% n-heptane. Occasionally using the wrong gasoline grade is harmless if corrected afterward, but prolonged use can have the following effects: Using higher-octane gasoline in a car designed for lower octane won't cause damage, but the increased octane may alter the fuel's ignition point, leading to delayed combustion, reduced engine power, and lower thermal efficiency. Using lower-octane gasoline in a high-octane car can cause engine knocking. The lower octane reduces the ignition point, causing premature ignition during the compression stroke. This creates resistance, making the engine run unstably. Mild knocking increases noise without significant damage, but severe knocking indicates serious engine issues, affecting driving stability and causing abnormal wear on pistons and cylinders, potentially leading to engine failure.
