Should Audi Cars Use 92 or 95 Octane Gasoline?

[OHeidi]

Audi cars should use 95 octane gasoline, and the correct gasoline grade is indicated on the inside of the fuel tank cover. The gasoline grade represents its anti-knock performance, and different cars use different gasoline grades depending on the engine's compression ratio. If an engine uses gasoline with a lower octane rating than specified, knocking may occur. Here are the relevant details: 1. Grade: The main difference between 92 and 95 octane gasoline lies in the content of heptane and isooctane. Specifically, 92 octane gasoline contains 92% isooctane and 8% heptane, while 95 octane gasoline contains 95% isooctane and 5% heptane. The gasoline grade also represents the fuel's anti-knock performance—the higher the grade, the better the anti-knock performance. 2. Anti-Knock Performance: Anti-knock performance refers to the gasoline's ability to resist knocking when burned in the engine, which is the primary indicator of gasoline's combustion efficiency. The octane number is the measure of gasoline's anti-knock performance—the higher the octane number, the stronger the anti-knock performance. Higher compression ratios lead to higher combustion chamber pressure, and if gasoline with lower anti-knock performance is used, knocking is more likely to occur. Since 95 octane gasoline has a higher isooctane content than 92 octane gasoline, it offers better anti-knock performance.