The regulations currently state that batches of gasoline are to be designated as summer or winter for purposes of compliance calculations under the Complex Model based on the RVP of the gasoline (§ 80.101(g)(1)(ii)).
However, EPA issued guidance in the RFG/Anti-dumping Questions and Answers document (8/29/94), which clarifies that batches are to be designated as summer or winter for use with the Complex Model based on RVP and the intended season of use. This clarification has been proposed in the July 11, 1997 NPRM at § 80.101(g)(3)(ii).
The Complex Model calculates emissions in mg/mi for each batch. Proposed § 80.101(g)(2)(i) of the July 11, 1997 NPRM clarifies that the exhaust toxics and NOx emissions in mg/mi are volume-weighted by batch to arrive at annual average values which must be less than or equal to the refiner's compliance baseline. (11/10/97)
This question and answer was posted at Consolidated List of Reformulated Gasoline and Anti-Dumping Questions and Answers: July 1, 1994 through November 10, 1997 (PDF)(333 pp, 18.17 MB, EPA420-R-03-009, July 2003, About PDF)