In 2007 and 2008, motorcycles and scooters, due to good fuel efficiency, attracted interest in the United States from environmentalists and those affected by increased fuel prices.[71][72] Piaggio Group Americas supported this interest with the launch of a "Vespanomics" website and platform, citing lower per-mile carbon emissions of 0.4 lb/mile (113 g/km) less than the average car, a 65% reduction, and better fuel economy.[73]
Other sources, however, claim that while motorcycles produce much less pollution in terms of greenhouse gases, a motorcycle can in some cases emit 10–20 times the quantity of nitrogen oxides (NOx) when compared to the NOx emissions of a car.[71][74] This is because many motorcycles lack a catalytic converter to reduce NOx emissions, and while catalytic converters have been used in cars long enough that they are now commonplace, they are a relatively new technology in motorcycles.[71] Many newer motorcycles (such as later models of the Yamaha R1 and Suzuki GSXR1000, as well as most BMWs which have included catalytic converers since the 1990s) now have factory fitted catalytic converters. Along with other technologies that have taken longer to appear in motorcycles (e.g. fuel injection, anti-lock brake systems),[citation needed] catalytic converters are becoming increasingly commonplace.
United States Environmental Protection Agency 2007 certification result reports for all vehicles versus on highway motorcycles (which also includes scooters),[75] 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.[76]
| Tier | Model year | HC+NOx (g/km) | CO (g/km) |
|---|---|---|---|
| Tier 1 | 2006–2009 | 1.4 | 12.0 |
| Tier 2 | 2010 and later | 0.8 | 12.0 |
The maximum acceptable legal emissions of hydrocarbon and carbon monoxide for new Class I and II motorcycles (50 cc–169 cc and 170 cc–279 cc respectively) sold in the United States are as follows:[76]
| Model year | HC (g/km) | CO (g/km) |
|---|---|---|
| 2006 and later | 1.0 | 12.0 |
Europe
European emission standards for motorcycles are similar to those for cars. New motorcycles must meet Euro III standards,[77] while cars must meet Euro V standards. Therefore, the difference in total pollution between motorcycles and cars that pass European emission standards would be small, certainly much smaller than the 10X factor claimed by the referenced LA Times article. Motorcycle emissions controls are being updated and it has been proposed to update to Euro IV in 2012 and Euro V in 2015[78]
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