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When it’s time to top-off the tank, drivers are confronted with a dizzying variety of choices at the pump. There’s premium gasoline, mid-grade, regular and – depending on where you live – some even offer ultra-high octane, with a rating of 94 or above.

Octane numbers, ethanol content and diesel get thrown in the mix, while TV commercials shout about special cleaning additives and better fuel economy. What’s a motorist to do? Is premium fuel worth the extra cost over regular? It’s more expensive so it must be better, right?
For the complete story on regular vs. premium fuel visit AutoGuide.com
 

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The article doesn't even mention what the higher octanes are for...fail.

Higher compression ratio engines require higher octane to prevent knocking and eventually detonation. Most newer engines (mid 90's and up) have knock sensors that retard engine timing to stop knocking if detected, so the average driver has no idea it even occurs. With our cars, putting 87 octane in may allow knock to occur, but the ECU would accommodate and most owners would not perceive the drop in power. Knock is more likely to occur in the supercharged or turbo cars since the air is already compressed and the 2zz has a relatively high 11.5:1 ratio compared to more run of the mill cars.
 
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