Report

The tricky business of octane, power, and MPG

Given tepid green-car sales numbers this year, consumers in the US aren't making the transition away from internal combustion engines too quickly. Regulations are still mandating cleaner emissions, though. In addition to downsizing and turbocharging, there's growing consideration about moving to higher-octane fuel to improve overall efficiency. In a new report, engineers at FCA, Ford and General Motors Powertrain are showing that it could work, too.

The major advantage to higher-octane fuel is that it supports higher compression ratios. That in turn can lead to more power from burning the same amount of gas. "Higher ethanol content is one available option for increasing the octane ratings of gasoline and would provide additional engine efficiency benefits for part and full load operation," the researchers write in the study's abstract. The authors even think it could be possible to update some modern vehicles' engine calibration to be optimized for the better gas.

While the benefits are there, we still have a long way to go before higher-octane fuel becomes a national standard. According to Green Car Congress, 87 percent of the gas sold in the US is regular grade 87-octane. Meanwhile, premium 91-93 octane makes up just 10 percent.

The various grades of fuel illuminate even more annoyances with the current system. For example, Ford generally recommends 93-octane for EcoBoost engines, and the power outputs that the company publishes are based on using it. However according to Green Car Reports, such premium gas is very difficult to find in some regions of the US, especially along the West Coast. The powertrains still run on lesser grades but with lower power output.

The researchers' discussion of possibly increasing ethanol in gas also comes during a heated debate on the substance. The current administration is pushing for less of the corn-based fuel in the coming years. Although, several presidential hopefuls might be favor of reversing that course.

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