WASHINGTON -- Premium-grade gasoline is enjoying a revival.
Premium gasoline’s share of total gasoline sales has hit its highest point in more than a decade, growing from only 7.8% in June 2008 to 11.3% as of September 2015, according to the Energy Information Administration's (EIA) Today in Energy report. While low gasoline prices are providing some of the lift, the agency believes most of the growth is tied to changing fuel requirements for light-duty vehicles (LDV) as automakers try to meet toughening fuel-economy standards.
The latest Corporate Average Fuel Economy (CAFE) regulations require LDV fleet fuel economy for model years 2017 to 2021 to fall between 40.3 and 41.0 miles per gallon (mpg). Standards will heighten to the 48.7- to 49.7-mpg range for model years 2022 to 2025. One way automakers can close in on these targets—beyond reducing vehicle weight, improving aerodynamics or selling more fuel-efficient electric vehicles and hybrids—is to downsize and turbocharge engines.
In turbocharging, a turbine driven by exhaust gas pressurizes the intake air, which enables the turbocharged engine to generate more power compared to a conventional engine. Because turbocharging enables smaller engines to meet or exceed the power and torque of larger engines, it allows automakers to downsize engines while improving fuel economy and not compromising performance.
However, turbocharging by design increases cylinder pressure and compression, which can cause fuel to prematurely combust—also known as engine knock—and possibly damage the engine. Design and operational features in the turbocharged engine help safeguard against engine knock, but so does the use of higher-octane gasoline. That’s because the higher the gasoline’s octane rating, the more it resists premature combustion. This is why automakers typically require high-octane premium in luxury and performance vehicles, which have higher-power engines.
While turbocharged vehicles made up only 3.3% of new gasoline-powered LDV sales for model-year 2009, their share more than quintupled to 17.6% by model year 2014. This growth in share is due less to rising consumer demand but and more to automakers’ increasing use of turbocharged engines in popular vehicle models. The EIA expects turbocharged vehicles’ share of the LDV market to continue to grow, hitting 83.3% by 2025.
As automakers introduce more turbocharged vehicles, they will likely require or recommend the use of higher-octane gasoline. Regular gasoline may damage engines that require premium-grade fuel and compromise the performance of those that have premium recommended. From model years 2010 to 2013, the share of gasoline LDVs that require or recommend higher-octane gasoline grew from 12.5% to 14.2%.
The EIA expects premium’s share of total gasoline sales to continue to grow “as automakers increase the use of turbocharging as one strategy to comply with increasingly stringent fuel-economy standards,” the report said.
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