Why Sunoco EPX Changes the Boost Game

The automotive hobby has finally embraced ethanol, moving past the days of fearing it would rot our carburetors to viewing it as the ultimate cheap race gas. It is now standard procedure for almost any high-horsepower Coyote build to run on corn. This shift has pushed fuel giants like Sunoco to develop specialized blends for racing, and at PRI 2025, they introduced Sunoco EPX, a new ethanol-based fuel designed to push the limits of boosted applications.

We spoke with Sunoco at the show to understand why a jug of fuel is better than what you get at the local station. Sunoco manufactures its own fuel and distills its own ethanol in Pennsylvania. They do not simply blend products from third-party sources. This allows them to strictly control consistency, which is the biggest enemy of pump E85. At the pump, ratios fluctuate wildly between seasons, with winter blends dropping ethanol content to help with cold starts. That is fine for a flex-fuel truck, but it can be dangerous for a tuned track car expecting a specific mixture.

Sunoco already addressed this with E85-R, a consistent 99-octane blend. However, they have taken it a step further with Sunoco EPX. This new formula is an evolution of E85-R that goes beyond 85 percent ethanol content and significantly increases oxygenation. The fuel features 34 percent oxygen by weight, up from the 30 percent found in previous iterations. This change drops the stoichiometric air-fuel ratio from 9.8:1 down to 9.4:1.

Because of the high oxygenation, Sunoco EPX does not carry a traditional octane rating, but it is engineered to handle over 30 psi of boost. It offers significantly more detonation resistance than the 99-octane E85-R. Shops like Evolution Performance have already been testing it in their 2020 GT500 and other development cars since early this year. For racers who need the cooling benefits of ethanol but demand the consistency of a pro-level race fuel, this is the new standard.