• Feb 13th 2009 at 8:02PM
  • 23
You may have noticed that a lot of new "green" cars not only lack a large carbon footprint but they also seem to be missing something else; a fourth wheel. Recently the three-wheel configuration has been appearing in various forms of vehicles, from the space-age Aptera to the a-bit-more-than-a-motorcycle Piaggio Mp3. With this seeming flood of tricycles sloshing about one question needs a clear answer: "Why do so many green cars only have three wheels?"

As you might imagine there are a variety of possible reasons why one would design a vehicle this way. Hit the jump to take a tricycular journey to find out why.

Sometimes referred to as a tri-car, three-wheeled conveyances have been with us since the beginning of the automobile. The very first motorcar, built in 1885 by Karl Benz and called the Benz Patent Motorwagon, featured only one wheel in the front and two in the back. Although his next design had four wheels and became the popular standard, trikes continued to be built from then until now.

There are two different ways to configure a three-wheeled vehicle. Placing one wheel in front and two in the back, à la the original, is usually referred to as the delta configuration. The reason most cited for using this format is cost. It is an relatively easy way to keep costs low since, not only is the steering mechanism cheaper to build and more simple to engineer, but it removes, obviously, the expense of a fourth wheel and all the bits that go along with that. The downside to this design is, just as obviously, stability. Although that might seem like a significant drawback, the truth is that there are millions of vehicles, mostly tuk-tuks, that are operated on a daily basis as the drivers understand their vehicles lack of cornering ability and stay within their safety parameters.

The other configuration, called the tadpole or reverse-trike, keeps two wheels up front and places one in the back. It shares with its somewhat ungainly tricycle brethren the advantage of decreased weight and lower rolling resistance, and is the preferred arrangement for builders of green vehicles. Usually much more stable than the delta - even more so if the front wheels tilt - this design allows for attempts to mimic the most aerodynamic form known; the teardrop. The less wind resistance a vehicle has, the less energy it needs to move forward.

The one other major reason for new manufacturers to go the three wheel route is regulatory. Simply put, three-wheeled vehicles are classified as motorcycles in the U.S. Therefore, they don't need to undergo the expensive safety testing that four wheel cars do. The cost of crashing several vehicles can be a major hurdle for a most start-up companies. Of course, with each state able to craft its own laws about the vehicles on its roads, there can still be some legal impingements to operating a tri-car in the U.S. However, with some lobbying effort these roadblocks, these roadblocks are slowly being removed, and the number of three-wheelers on American roads will very likely go up in the coming years. To get a good idea of the vehicles you may see, check out the galleries below.

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    • 1 Second Ago
      • 6 Years Ago
      After trying to design, fund and build an electric and/or hybrid electric car and get a company off the ground I found one thing to be true: nearly all of these cars were built as three wheelers because it cost many millions of dollars to go through all the regulations to get a 4 wheel (real car) on the road. I got to talk with, and in many cases got to know fairly well, almost all the folks who started up and owned all these little companies. And all of us agreed that once we could get started and afford it, we'd go to a "real car" as our long term strategy. Of course we didn't like to admit that while justifying our three wheel efforts. LOL

      Seriously guys, you should see how much it really cost to get all the ABS, side impact testing, air bags, active and passive safety systems, etc into a certified car. I finally understood why the big guys move so slow...there is no other way to move in this industry with all the regulations and you better have DEEP pockets.
      • 6 Years Ago

      This car is banned from autoblog green.
      • 5 Years Ago
      It always astounds me to see how many people have good comments but man I get tired of stupid people and uneducated crap that comes from there lips
      here is a three wheeled car designed to get high mileage at highway speeds, it will do 135 mph, it was recently verified by a university to get 275 mpg city and a 0 to 60 mph in under 5 seconds, it is front wheel drive and can out handle any 4 wheeled car on the market, check it out www.futurevehicletechnologies.com
      • 6 Years Ago
      What's the problem? Millions of American ride motorcycles every day that are no safer than these trikes.
      • 6 Years Ago
      Three wheels or four wheels is probably a matter of reducing the production price, or something like that.

      I just want to know, why every single one of these cars is so painfully ugly.

      I can really see myself drive an electric car within a few years, but I would never ever consider driving one of these i bright daylight. The only one I could consider is Volt, and of course Tesla or Karma. But that's just wishfull thinking.

      Just a stupid comment from me...
      • 6 Years Ago
      3 wheelers are pretty nice pothole detectors.
      • 6 Years Ago
      I like to sleep at night... that's why we designed the Persu with a driver's airbag, 3-point restraints, steel rollcage, side impact rails, safety glass, crumple zones, and ABS brakes. And yes, we're doing industry standard crash testing, even though it's not required of us. Seriously... would you drive a vehicle that hadn't been crash tested?

      I'm also one of those millions of Americans who rides a bike (a very nice BMW, actually), and I can assure you the Persu will be as safe as a car in comparison. We wouldn't sell it otherwise -- and we wouldn't expect people to buy one if it wasn't.
        • 6 Years Ago
        Did Aptera ever follow through with the crash tests that were supposedly taking place last summer?
      • 6 Years Ago
      If these 3 wheeled cars ever achieve any level of popularity, we'll begin reading about them being death traps as occupants are killed in accidents that would be survivable in any contemporary 4 wheeled vehicle. Also, depending on the state, the driver and passengers will be surprised when they are ticked for not wearing helmets.

      From a space efficiency point of view, a vehicle with four wheels at the corners provides significantly more usable space than a 3 wheeled one.

      Circumvention of automobile safety standards are the only reason that these vehicles are built with three wheels.
        • 6 Years Ago
        That echos my thoughts. If they're being built to cut corners in an effort to get something to the market quicker and cheaper, then where is the safety? I understand on a motorcycle there is essentailly nothing between me and whatever is about to hit me. Sitting in one of these vehicles would seem to give a (false?) impression that you are safe like being in a car.

        I can see one major accident involving a vehicle of this type and that manufacturer will soon be no more as the lawsuits start. It won't take much bad press coverage of this to hurt all the rest too.
      • 6 Years Ago
      Here is a nice explanation of way the 3 wheel layout is a good way to go. A 4 wheel layout has a energy efficiency reduction of 44%.

      • 6 Years Ago
      Can't wait for Piaggio to come up with a covered version of the MP3. Would be perfect for the city.

      Something like a cross between the MP3 and the Lumeneo Smera:


      • 6 Years Ago
      Why do so many “green” cars have only 3 wheels?

      That’s simple:


      It simply cost too much to comply with the Statist central planning crash tests.


      A car that will comply with the Statist central planning crash test weighs more which lowers its fuel mileage.


      It takes MUCH more time to product a car that will comply with the Statist central planning crash test and any fool knows that time IS money.

      Statist central planning works for GIANT corporations who can afford to comply and that’s why they LOVE big gov't who will regulate the smaller start-up firms out of business or into another sector of business. In this case, 3-wheel vehicles or NEV toys.

      Corporatism and Statism work hand in hand to create monopolies that will work together to kill the competition. Think Big Auto and Big Oil.

      THAT is why corporations return $BILLIONS in tax incentives and direct payout "R&D" money BACK to congressmen (bribes) to "help" them with their campaigns or "lobby" them for their "support" for MORE regulation and MORE bailout redistribution to strengthen their monopolies and kill the small startup competition.

      Politicians love the money and power they get from “helping” someone and giant corporations love the profits from monopoly.

      I don’t understand why liberals can’t figure this out? Any child could clearly see that it’s all about CONTROL, money and power. Even the child who NEEDS a big brother.
        • 6 Years Ago
        You seem correct in many aspects, and woefully confused in others. Equating big government with liberalism is nonsense. The last eight years of "conservative" government has resulted in a much larger government and huge deficit spending. Many government regulations can provide small start up firms a chance. The recent administration has catered to "big corporations" and was obviously not a liberal based agenda. Timmy. Try basing your thinking on objective information versus pure emotion and assumption.
        • 6 Years Ago
        Don’t be fooled by the media!

        There was nothing "conservative" about the NeoCons and the biggest increase in gov't reach in US history that was the last 8 years under Bush. The Republican party has been hijacked by the NeoCon traitors.

        REAL conservatives won’t take your money, tell you what to do, think or say and they would NEVER start a war, build an empire, redistribute wealth or tell you how to raise your children. They just want to leave you alone as long as you leave them alone.

        To learn more about what a REAL conservative is, you need to go here: http://www.campaignforliberty.com/

        You are only free when both Big Corporations AND Big Gov't are NOT standing on your neck or FORCING you to accept their "help".

        Personal Freedom REQUIRES Personal Responsibility and THAT is your civic duty!
      • 6 Years Ago
      It seems to me that they would make great city cars to reduce emissions in crowded areas. But I think they would only work in places with really sunny weather. If it snows you can't go on the highway because your drive wheel would be in the center track of snow and if it rains your front two tires would be splashing water in the way of your back drive wheel.

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