Using portable emissions equipment, a wide sampling of cars and bikes from the 1980s, 1990s and 2000s and with the help of Dr. Kent Johnson of UC Riverside, the Mythbusters team claims they proved motorcycles are dirtier than cars.

Doing so meant gathering data in real-world driving conditions along a 75-percent freeway, 25-percent city driving loop in and on the vehicles from different eras. The results of that test proved one thing that everyone should already know: motorcycles use less fuel than cars.

They also produce less carbon dioxide than cars, which accounts for 90 percent of a vehicle's emissions. Where cars pull ahead, though, is in the amount of other noxious gases they produce. The Mythbusters found that bikes produce tons more hydrocarbons, which are carcinogenic; nitrogen oxides, which cause acid rain; and carbon monoxide, everyone's favorite odorless deadly gas. Astoundingly, the 'busters claim bikes produce up to 8,000 percent more carbon monoxide than cars. Yes, 8,000 percent.

A controlled test on a track using a small displacement, fuel injected modern bike didn't give two wheelers the help the 'busters thought it would.To give bikes another chance, Jamie and Adam built an aerodynamic frame to make the modern bike sip even more gently through the wind. The result, predictably, was that the emissions got a little better, but were still worse than the car's. See the videos for yourself after the break.






I'm reporting this comment as:

Reported comments and users are reviewed by Autoblog staff 24 hours a day, seven days a week to determine whether they violate Community Guideline. Accounts are penalized for Community Guidelines violations and serious or repeated violations can lead to account termination.


    • 1 Second Ago
  • 64 Comments
      Hazdaz
      • 3 Years Ago
      I think I speak for everyone when I say: Mmmm Kari. (and she post-preggors in that video and she still looks that hot!?!?)
      NissanGTR
      • 3 Years Ago
      I completely missed the 2nd and 3rd part staring at Kari Byrons bigger boobs.
      Doug Danzeisen Sr
      • 3 Years Ago
      Figures don't lie, but liars do figure. RacerX808 is right on the money, most new cycles have fuel injection and catalysts, so I think we are comparing apples and oranges for most of us. Of course cars from the 60's and 70's would pollute more also, in fact, not until I believe 1963 that automakers stopped venting crankcase vapors directly to the atmosphere. The average bike also is ridden much less than the average automobile. It is common to see 1980's bikes for sale with under 10,000 miles on them- so total output per lifecycle is actually a lot less. How do chain saws and weed wackers compare?
        waetherman
        • 3 Years Ago
        @Doug Danzeisen Sr
        Maybe you didn't watch the full segment; they tested older cars, older bikes, newer cars and newer bikes, including fuel-injected ones with catalytic converters. And they did it all to test under the premise that people are buying motorcycles these days because of the economy and to be more green. So while it's true that you often see motorcycles with far fewer miles on them than cars of a similar age, the test was really about efficiency and emissions for a mile-for-mile comparison, not a lifetime impact study for various vehicles. And that makes sense; if someone is commuting 40 miles a day and they have a motorcycle and a car in their driveway, they want to know which is going to be cheaper and which is going to pollute less for that trip. What the Mythbusters found is that bikes are more efficient (no surprise there), but not necessarily less polluting when it comes to certain gases. As a rider, I found that pretty interesting.
        Rotation
        • 3 Years Ago
        @Doug Danzeisen Sr
        Chain saws and weed wackers are also regulated by CARB due to their emissions. The EPA tried to even add catalytic converters to lawn mowers but the lobbyists blocked it. Your attempt to take the high side failed. As to the idea of the average bike being ridden much less. We are talking about levels of emissions so much higher than putting on 1% as many miles may still mean the motorcycle pollutes more in a year than a car.
      Danaon
      • 3 Years Ago
      This makes sense. CO2 emitted is directly proportional to how much fuel is burnt, but NOx and particulate emissions are not. Both of the latter are greatly reduced by current emissions equipment on vehicles, but often you can't really put all of the same controls on smaller engines. 2 stroke engines like weedeaters and chainsaws also emit a lot of NOx and particulate, due to few emissions controls + burning more oil as a 2 stroke. Large diesel ship engines are generally 2 stroke as well, meaning they are a huge amount of these emissions. One large tanker ship emits about as much in a year as about 750000 cars.
      Krishan Mistry
      • 3 Years Ago
      Maybe it is down to the fact that many bikes dont have catylitic converters? Or the higher compression (sport bikes) causes a less clean burn? Pretty amazing that a bike pollutes 8000x more CO than a car, even if it is efficient. Still, a sport bike can get 50+mpg, for 15K, and be as fast as a 15mpg 300K supercar, which is insane.
        speedracerx808
        • 3 Years Ago
        @Krishan Mistry
        Actually pretty much all new bikes have cats on them. California models have way more regulations for emissions.
        2 Wheeled Menace
        • 3 Years Ago
        @Krishan Mistry
        Actually... A car would put out TONS of carbon monoxide if it weren't for modern emissions controls. Given equal emissions controls, a 2 wheeler would have fantastic emissions... because the carbon monoxide would be converted to carbon dioxide. Really doesn't have much to do with the way the motor burns.
          Hazdaz
          • 3 Years Ago
          @2 Wheeled Menace
          I think the way the motor burns does have something to do with it (to a certain extent), its just that bikes are allowed to get away with much lower emissions limits than cars, so their emissions controls (cats) aren't as advanced. Like someone said above, in Europe, bikes have to pass the same regs that cars do. I personally would be curious to know what those extra emissions controls are. How much bigger/heavier is a EURO3 exhaust versus the ones we get here in the US and how much more does that add to the cost of the bike. If we were talking about 10 or even 20% more emissions from a bike than a car, then I think for the most part, it would be a non-issue since there are so few bikes, but when bikes are allowed to dump 100 or even 1000% more, then I could see it being a problem.
          Hazdaz
          • 3 Years Ago
          @2 Wheeled Menace
          @ 2 Wheeled Menace "Should" and does are two completely different things. If the emissions coming out of any engine are not reduced, then yeah, a small engine that is even 2X as efficient will still pollute more of certain pollutants than an engine twice the size that has more emissions controls on it. As it is now bikes and cars do not run the same emissions controls (at least in the US), so bikes are more fuel efficient than cars, but not cleaner.
          2 Wheeled Menace
          • 3 Years Ago
          @2 Wheeled Menace
          But think about this. A motorcycle engine is typically 1/3rd - 1/5th the displacement of a car's engine. It should not be polluting more !!
      johnbravo6
      • 3 Years Ago
      Since when is mythbusters credible?
        Andre Neves
        • 3 Years Ago
        @johnbravo6
        Yeah, you're right. Better stick with Consumer Reports and random car magazines :-\
      Bart
      • 3 Years Ago
      Since I've already seen the show we can conclude bikes are way more polluting since CO2 is harmless (except to the haoxers) but NOx and CHx's aren't. Also how many commenters didn't even even bother checking if the bikes had a catalytic converter.. hint; some do. Ignorance isn't bliss guys, just makes you look like an ass.
      Rob Cook
      • 3 Years Ago
      Catalytic converter, on my SuperWideElectraFatBobBoyMidnightScreaminSportster-XLVFHTWTFBBQ? Come on now, how will I get my classic 'potato-potato' with a cat? You stinking liberal don't you realize LOUD PIPES SAVE LIVES! DO YOU WANT ME TO DIE!!!!?!?!???!!!!??!?!?!!
        G. Grialou
        • 10 Months Ago
        @Rob Cook

        yes......;)


        Jess Bailey
        • 3 Years Ago
        @Rob Cook
        Except, you know, you can only hear them from behind. Last night a bike woke me up and could hear him going for at least a mile down the road. It pissed me off. And I've been riding since I was 5, so I love bikes, but loud pipes are just unnecessary.
          G. Grialou
          • 10 Months Ago
          @Jess Bailey

          I'm a "rider".  A neighbor of mine used to espouse the "loud pipes save lives"......until he got t-boned in an intersection down the street from me!  When I brought this to his attention.....his answer was: dead silence!  Also, is there some reason that saying is used by Harley riders almost exclusively?  Answer:  neandrethals.......on neandrethal bikes. 


          NeutronStar73
          • 3 Years Ago
          @Jess Bailey
          I agree completely. Loud pipes don't do anything but make a lot of unnecessary noise and prove that you are an attention *****. I ride bikes and it irritates the living daylights out of me that some jerkweed Harley rider is a mile away and I have to turn up my radio in MY HOUSE because of his need to be loud.
        DWR
        • 3 Years Ago
        @Rob Cook
        Completely correct, you cannot really see a motorcycle on the road so hearing them is the next best thing. My neighbor rides with no muffler just because of this, and even though it wakes me up in the morning and I hate it, I don't blame him and will not complain.
          G. Grialou
          • 10 Months Ago
          @DWR

          Loud pipes do not save lives......they just piss people off!  

      jj360
      • 3 Years Ago
      Their job is to 'prove' commonly held beliefs wrong for entertainment, so that's what they set out to do therefore nothing they do is partial. If you take their results as facts you should not be allowed to reproduce.
        Brandon Frazier
        • 3 Years Ago
        @jj360
        that's not their job, They confirm a huge number of myths as well. If you have ever watched the show (which its clear youre not a usual viewer) you would know that they are as objective and unbiased as possible. The show is more about the scientific method applied to these concepts( myths) rather than proving them right or wrong....next time.....dont talk ahead of yourself so boldly.
      waetherman
      • 3 Years Ago
      I found this interesting, but was ultimately pretty disappointed with this segment. What they failed to do was explain why there was that difference in emissions. And of course they jumped right to making the motorcycle more aerodynamic which made no sense - there was no way they were going to reduce some gases 8000% by improving efficiency, and they knew it before they even started the experiment. So the whole segment was just kinda unexplained and bad scientific method for the sake of doing some kind of A-Team construction on a very efficient motorcycle mod. Not what I've come to expect from the MythBusters.
      John
      • 3 Years Ago
      It seems like they could of picked a better motorcycle or try at least two different ones but whatever. I am still baffled how Jamie can say CO2 is a pollutant with a straight face. So I guess we all have to hold our breath for eternity.
        wiggy
        • 3 Years Ago
        @John
        They ran 4 different motorcycles. Seriously, are you people not even watching the entire episode?! It's like everyone in here has chronic Uhmerikan Syndrome. "I read/watched the 1st eighth of the story, and I feel that I have enough of the article/show under my belt to make a relevant comment." What's this "better motorcycle" that you speak of anyway? They ran 1 from each decade (80's, 90's, 00's) AND a brand new bike that should be (and was indeed) the most efficient of most anything available today.
      ftpaddict
      • 3 Years Ago
      Or, you know.. just add a catalytic converter to the bike and there we go.
        • 3 Years Ago
        @ftpaddict
        [blocked]
    • Load More Comments