We know that start-stop technology – which shuts down a car's engine when the car comes to a halt – is going to be available in more and more vehicles. BMW, Mercedes and Porsche already have the technology on non-hybrid vehicles and Jaguar and Kia will introduce it soon. Ford, too, is adding start-stop to non-hybrid models for a modest fee. In the 2013 Fusion (pictured), it costs just $295. But how many vehicles soon get all quiet at red lights? Around 8 million in North American by 2017, says a study by Lux Research, as automakers get ready to meet higher CAFE standards. AAA is getting out in front of the questions by issuing answers to questions it thinks drivers will have about why their car turns "off" so often. Here's some of what the AAA has to say.

Start-stop can increase fuel economy by up to 12 percent. The engine is shut off under different circumstances in manuals and automatics (transmission in neutral, clutch released in manuals; vehicle stopped for several seconds, brake pedal applied for autos). In both cases, once the driver makes moves to go again, the engine fires up. Alongside worries about HVAC performance and the potential higher cost to replace the bigger batteries start-stop required (which gas savings should more than cover) the biggest downside AAA can come up with is driver expectations: "The engine stop-start transitions must be smooth and seamless, and drivers new to the technology will need to learn that engine shutdown at idle is a normal thing and not a sign of a problem."

One of the bigger questions we have is why the U.S. is so far behind the curve on this issue. Over 40 percent of new vehicles sold in Europe and Japan have start-stop. The answer, it turns out, is the EPA.
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More Than Eight Million Cars Expected to Have Stop-Start Systems by 2017, AAA Experts Offer Advice on this Fuel Saving Technology

New technology shuts off the engine when vehicle is stopped in traffic

ORLANDO, Fla., Aug. 9, 2012 /PRNewswire-USNewswire/ -- The stop-start system, a technology that shuts off a vehicle's engine when stopped in traffic, is now making its way to the U.S. from overseas where such systems are already in common use. Other names for this technology include idle elimination, idle-stop-go, and micro-hybrid. Lux Research predicts that more than eight million vehicles in North America will be equipped with engine stop-start systems by 2017. What does this mean for American motorists? AAA experts examine the technology.

Early versions of stop-start technology date back to the 1980's, and today over 40 percent of the new cars sold in Europe and Japan use this gas saving technology. "Engine stop-start isn't a brand new technology, but the latest systems benefit from significant advances made in the last few years," said John Nielsen, AAA's Director of Automotive Engineering and Repair. "This technology is only going to gain momentum as vehicle manufactures work to meet the more stringent Corporate Average Fuel Economy (CAFE) standards set for 2016."

The information below on engine stop-start systems comes from the recently formed AAA Automotive Engineering team, which is based at the association's national office in Heathrow, Fla. The goal of the team is to provide members and other consumers with unbiased assessments and advice on new automotive technologies.

Here, from AAA's automotive experts, are answers to a number of common questions about engine stop-start systems:

What is stop-start? Stop-start technology automatically shuts off the engine when a driver is stuck in traffic or waiting for a red light to change. By doing so, the system can improve fuel economy up to 12 percent and contribute to a reduction in vehicle exhaust emissions.

How does it work? With an automatic transmission, engine shutdown occurs when the vehicle is stopped for several seconds with the brake pedal applied. With a manual transmission, shutdown takes place with the transmission in neutral and the clutch released. As soon as the brake pedal is released, or the clutch pedal is depressed, the engine restarts automatically.

How much does it cost? On some models, the stop-start system is standard equipment and its cost is included in the vehicle price. Where stop-start is offered as option it generally costs around $300.

How much can it save? If gasoline costs $3.75 per gallon, the owner of a car that normally gets 20 mpg and is driven 12,000 miles per year would save an estimated $167 per year in fuel costs if the vehicle were equipped with an engine stop-start system. In this case, the system would pay for itself in less than two years and offer ongoing savings thereafter.

Are there any downsides to stop-start? A major challenge in developing stop-start systems has been engineering the systems to meet consumer expectations. The engine stop-start transitions must be smooth and seamless, and drivers new to the technology will need to learn that engine shutdown at idle is a normal thing and not a sign of a problem. In some vehicles, heating and air conditioning performance could suffer if the engine remains shut down for an extended time. Finally, the larger and more powerful batteries that are required for stop-start systems will be more expensive to replace when the time comes.

What American market vehicles offer stop-start today? All hybrid cars have stop-start capability, although they use a different technology than the systems on conventional powertrains. The first non-hybrid stop-start systems in the U.S. market are on 2012 highline vehicles from BMW, Mercedes and Porsche. For the 2013 model year, Jaguar will join that select group, but stop-start systems will also become available on popularly priced models from Ford, Kia, and possibly others. Even trucks will start to see some systems with Dodge adding stop-start to its V6-powered Ram 1500 pickup for a one mile per gallon fuel economy improvement.

As North America's largest motoring and leisure travel organization, AAA provides more than 53 million members with travel, insurance, financial and automotive-related services. Since its founding in 1902, the not-for-profit, fully tax-paying AAA has been a leader and advocate for the safety and security of all travelers. AAA clubs can be visited on the Internet at AAA.com.


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  • 19 Comments
      Dave D
      • 2 Years Ago
      Why would the EPA adjust their test to show how stop/start benefits mpg in city driving? It's not like we ever drive in city traffic in America or anything. Oh wait...Yep, they're totall @$$holes.
        sirvixisvexed
        • 2 Years Ago
        @Dave D
        Basically every agency is an overcomplicated bureaucracy. You can't just think something logical and true and then throw your thought at the system and have it be absorbed.
      Nick
      • 2 Years Ago
      As much as I like start/stop, I believe the system would work much better in tandem with a low-speed EV mode, allowing one to move the car a bit without having the engine turn on every time. Think of it this way, you're driving on the fwy and need to slow down to a stop, and traffic is at a standstill. About 5 seconds later, the car in front of you moved 5 yards forward, and so on and so forth (the so-called stop-and-go situation). With a low speed EV mode, one could move the car on electrons.
        JP
        • 2 Years Ago
        @Nick
        That's called a hybrid. Yes it's better than SS, which is simply a drop in the bucket.
      garrypal
      • 2 Years Ago
      One would think that cylinder de-activation would be a better alternative to start-stop. Apparently the way de-activation is being deployed now however is only during cruising.
        Nick
        • 2 Years Ago
        @garrypal
        Why would MDS be better? It also adds extra weight and moving parts to the drivetrain....reducing efficiency when all cylinders are firing.
      2 Wheeled Menace
      • 2 Years Ago
      This is an idea who's time had came a decade ago. A $300 investment into each car could easily pay off early into the lifetime of the car. Makes you wonder why we invest in other things!
        JP
        • 2 Years Ago
        @2 Wheeled Menace
        In reality the batteries used to support the system often cannot accept enough charge fast enough after a short period, and the SS system shuts itself off, or you need a new battery. IF you use a battery than can handle the demands, such as lithium, it costs more.
        sirvixisvexed
        • 2 Years Ago
        @2 Wheeled Menace
        And you still have a working stop/start system when you're done with it, which will retain some of it's $300 value, along with more than paying for itself through use
      Baldur Norddahl
      • 2 Years Ago
      "The engine stop-start transitions must be smooth and seamless, and drivers new to the technology will need to learn that engine shutdown at idle is a normal thing and not a sign of a problem." I have tried the old WV Lupo 3L which pioneered the start/stop. The engine shutting down surprised me at every stop... And the restart is quite noticeable too. I also recently tried the new Toyota Yaris Hybrid. It is a total different experience. Here you never notice it at all. Indeed that car will shutdown the engine long before reaching the stop. You barely notice that it is happening at all. And the car being total quiet at standstill is so cool.
      Nick
      • 2 Years Ago
      Start/Stop could be taken further. How about the engine shuts off whenever you take the foot off the gas pedal? That would allow one to coast for long distances, gas free..
        Baldur Norddahl
        • 2 Years Ago
        @Nick
        All modern cars turn off the fuel injection when coasting. What makes start/stop different is that a non-moving car can not simply use the car momentum to restart. A moving car still has the engine spinning and to restart it simply needs to start injecting fuel again.
          Nick
          • 2 Years Ago
          @Baldur Norddahl
          Baldur I see, thanks for the clarification. From what I noticed, disengaging the clutch and coasting (especially on a slight downward slope) will take you 10x farther than when keeping it engaged. Unfortunately, I do not believe that today's start-stop cars shut off and disengage the tranny when coasting. I drive a 2012 A6 and it only shuts off when stopped (after a few seconds).
          Nick
          • 2 Years Ago
          @Baldur Norddahl
          Do you mean that a car will not burn a drop of oil as soon as the foot is taken off the gas pedal? Then how come it stays on when I reach a stop? What I meant (more precisely), is that the tranny should switch to Neutral as soon as the gas pedal is released. This would allow one to coast much, much farther.
          Baldur Norddahl
          • 2 Years Ago
          @Baldur Norddahl
          @Nick The car will not burn a drop of oil until the revs get below stall-speed. At that point it will start burn oil to keep the engine going at idle. Here where most cars are manual, a recurring topic is the debate whether it is most fuel saving to disengage the clutch or not when coasting. Disengage lets you coast longer but the engine will burn fuel to run idle. Keep it engaged lets the engine cut the fuel supply but causes the car to coast slightly shorter. I see your point in disengaging the clutch (or go to neutral) and do an engine shutdown. I expect they are already doing that on cars with start/stop.
      Ryan
      • 2 Years Ago
      The EPA should have mandated it on every car. I'll blame the EPA for that, not because automakers didn't want to spend money that couldn't be used in their marketing to show that it gets better mpg.
      • 2 Years Ago
      Damn, that Fusion is one sweet looking ride.
        Letstakeawalk
        • 2 Years Ago
        Looks very similar to, but more aggressive than, the Model S. http://strumors.automobilemag.com/files/2009/05/18113179.jpeg
      mchlrus1
      • 2 Years Ago
      If you watch Gallery 63 on Discovery, the Ford expert who appraises an old 50's T bird brought the new Fusion with him. I had trouble processing that it was an actual Fusion because they aren't out yet. It is very slick!
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