Motorcycle

United States Environmental Protection Agency 2007 certification result reports for all vehicles versus on highway motorcycles (which also includes scooters), the average certified emissions level for 12,327 vehicles tested was 0.734. The average "Nox+Co End-Of-Useful-Life-Emissions" for 3,863 motorcycles tested was 0.8531, for a difference of about 16%, not the claimed 10X factor. Likewise, if one looks at how many of the 2007 motorcycles tested were also catalytic equipped, 54% of them, 2,092, were equipped with a catalytic converter.
United States emissions limits
The following table shows maximum acceptable legal emissions of the combination of hydrocarbon and nitrous oxides, as well as carbon monoxide, for new Class III motorcycles (280 cc or larger displacement) sold in the United States.