

According to a report in Automotive News, GM, Ford, and FCA are working with the U.S. Council for Automotive Research on a plan to change from three octane choices to just one: 91 octane. Dan Nicholson, GM’s vice president of global propulsion systems, sung the praises of the plan in testimony before the House Energy and Commerce Committee’s environment subcommittee last week.

The goal is to make 95 RON (Research Octane Number) gasoline the new standard. Gas with a 95 RON is equal to somewhere around 91 (R+M)/2 octane fuel. The latter is the measurement we use in the States, while RON is used throughout most of the world. Our figure is also called the Anti-Knock Index (AKI) and it's derived by adding the RON measurement to the Motor Octane Number (MON) and dividing that result by two. So, our AKI octane number is typically a bit lower compared to the RON figure seen elsewhere.

By bringing our standard low-tier gasoline octane rating up to 95 RON, automakers say we'd see an across-the-board 3-percent improvement in fuel economy. This would also lead to a less-than 3-percent rise in the cost of fuel. It balances out if you're spending a fraction more to fill your car while also spending less time doing so.

With refineries able to focus on fewer octane levels, cost savings could be realized further up the fuel-production chain. But then again, when have oil companies ever given away anything for free? David Filipe, vice president of Ford's powertrain engineering, said the cost should not go up by more than 5 cents per gallon. Right now, 91 octane is usually premium fuel that can cost 50 to 80 cents per gallon more than regular.

To take advantage of the higher octane fuel, however, we're going to need engines with increased compression ratios. That's how we'll see the rises in horsepower, torque, and overall engine efficiency that will bring about the benefits being touted by the automakers. According to Nicholson, "making 95 octane the new regular aligns the U.S. with Europe and is one of the most affordable ways to boost fuel economy and lower greenhouse gas emissions."

Today, most gas stations typically offer three choices, but the average consumer is likely to select the cheapest option. If we make that cheapest option a better quality fuel, it will lead to fewer emissions, more efficient engines, and clear fuel economy gains.

Octane can be increased by adding more ethanol or reducing heptane, the Automotive News report states. Adding ethanol, however, would reduce fuel economy, not improve it.