Most heavy vehicles run on diesel fuel, which contains sulfur.
The EPA contends that sulfur content in diesel should be reduced by 97 percent to clean up the environment. Ed Murphy of the American Petroleum Institute said he doubts whether the existing technology can even remove sulfur from diesel to the extent that the EPA wants. The estimated cost to the industry of implementing the EPA plan is unknown, according to Sternfels, but it could run into several billion dollars. Pages will open in a new browser window External sites are not endorsed by CNN Interactive.