All remained well below acceptable state standards and were close to those seen from new car engines. The increases were expected and normal, said Dan White, quality assurance and training manager for the emission technical center. The decrease was unusual. He and Jerry Medinger, an air management specialist with the Department of Natural Resources, said normally all emission figures would be lower with reformulated gas. The biggest variable in any test is the engine and the conditions affecting it.
Temperature is a key variable, while humidity also can play a role.
In our test, the car was cold and driven directly to the test site each time. Humidity did not seem radically different. In my car's test, because the particulates were so minuscule, he said the variations were not terribly significant. In addition, experts say, my gas mileage savings was a little higher than what they would expect. In reality, the emissions test readings actually showed my car running at a level that would get me 27.5 mpg on the non-reformulated gas, compared with 30 mpg on the reformulated fuel.