When looking for green transportation, does it make sense to opt for two wheels instead of four?
Motorcycles weigh significantly less than cars, and generally have smaller engines.
That means they use less fuel than the typical car, and they also require fewer raw materials to make.
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But does that mean motorcycles are greener than cars overall?
The answer to that question is a bit complicated.
This question was brought into the limelight back in 2011, when the Discover Channel show MythBusters aired a segment on the relative environmental impact of cars and motorcycles, which the Los Angeles Times covered in detail at the time.
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Both groups of vehicles were equipped with Portable Emissions Measurement Systems (PEMS), the standard hardware used for on-road emissions tests.
The results showed that motorcycles were generally more fuel efficient than cars, and emitted less carbon dioxide.
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But they were also found to emit higher levels of hydrocarbons, carbon monoxide, and nitrogen oxides.
These results made it difficult for the MythBusters to draw any clear conclusions about which type of vehicle is greener.
In the real world, though, it's likely that most cars are achieving the lowest level of emissions possible, but that may not be the case with bikes.
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Less-restrictive exhaust systems that increase sound and enhance performance—but sometimes discard emissions gear—are a popular modification.
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For buyers looking for the greenest possible vehicle, the solution may not be to switch from four wheels to two, but to switch from gasoline to electric.
As with cars, gasoline-powered motorcycles will never be able to achieve the low overall emissions of all-electric bikes.
[hat tip: Don Scott]