The issue arises from vapor volatility in ethanol blends. In extreme cases it can cause vapor lock in car engines, causing them to stall. Florida follows the industry standard set by the American Society for Testing Materials. Marathon says ASTM’s standard for E10 sets too high a bar and prefers another set of standards that certifies the ethanol and the gasoline separately, before blending.

Marathon wants the state to modify the standard so its fuel would comply. The Houston-based company points to other states where regulations have been modified to suit E10 suppliers. Among them are Arkansas and Louisiana, which have climates similar to Florida’s.

Florida’s Department of Agriculture and Consumer Services says it is unwilling to tweak state regulations until it gets more scientific data to satisfy a fuel vapor issue, which officials fear could cause vehicles to stall in hot weather.

“We are at an impasse,” said Jay Levenstein, deputy commissioner of the Department of Agriculture and Consumer Services.