Engine manufacturers, oil producers, and refiners all are asking the EPA to make the potential regulations less stringent, and environmentalists are worried that the EPA may cave to the groups' pressure. The manufacturers are saying that the stricter testing requirements would be impossible to meet, as they apply to all operating conditions including differing altitudes and extreme temperatures. While they want a softening of the testing requirements, the manufacturers are in support of the second, ultra-low sulfur levels regulation, saying the low levels are crucial to the development of the sort of clean engines the EPA wants. However, the oil industry and refiners are arguing that it will be impossible to distribute the ultra-low sulfur diesel within the EPA time frame. The environmentalists are demanding that the EPA stand tough, saying that these regulations are long overdue.
Truckers feel caught in the middle.