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Five Things You Need To Know About Stop/Start Systems

 
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2012 Kia Rio Sedan

2012 Kia Rio Sedan

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You’re probably already familiar with the effect that a hybrid drivetrain has on fuel economy, but now one of the key concepts of a hybrid drivetrain -- the ability for the engine to turn off and on automatically at stoplights -- is being introduced in conventional gasoline-engined cars.

Called stop/start technology, these systems can improve your fuel efficiency as well as improve air quality and cut pollution. 

But what is stop/start technology, and do you need it? 

Check out the five things you need to know about about stop/start systems below to see if you need it in your next car.

Stop/start cars aren’t hybrids

Stop/start, sometimes called light hybrid by automakers, stops and starts your car automatically when it isn’t needed, but unlike the system found in a hybrid car it isn’t backed up by a large electric motor and high-voltage battery pack.

In a hybrid car, slowing down for a stoplight normally switches off the car’s gasoline engine while recapturing the car’s kinetic energy into its high-voltage traction battery pack using regenerative braking.

But in most non-hybrid stop/start systems, the car’s engine is switched off when you slow down below a certain speed -- normally a few miles per hour -- with the car’s conventional friction brakes slow you down rather than a regenerative braking system.

When it comes to starting the engine again, a hybrid car uses its built-in electric motor to get the car moving before the engine is started again.

In a non-hybrid system, the traditional alternator and starter motor combination is replaced with a heavy duty alternator capable of both charging the car’s 12-volt battery as well as starting the car. 

Stop/start cuts fuel bills, saves engine, reduces emissions

Gas pump

Gas pump

When you sit at stoplights in a traditional car, the engine continues to run even while it is standing still, meaning the longer your car is caught in traffic the more fuel it uses. 

And while your car’s alternator and on-board electrical system gets charged when the engine is running, modern battery technology and more efficient car accessories mean that even if you’re sat in traffic for a long period of time, your car’s 12-volt battery shouldn’t go flat.

By switching off the engine when the car isn’t moving, a stop/start system can drastically lower air pollution and emissions, especially in cities where there tends to be a lot of congestion. 

Stop/start also reduces engine wear, lowering maintenance costs and minimizing the risk of engine overheating when waiting in traffic on a hot day.




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Comments (17)
  1. Nice write-up! I like that fact that Kia is bringing stop/start to the masses and packaging it in the EX package rather than the SX. Nothing feels more wasteful than sitting there idling!
     
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  2. One sad fact is that the current cycles used by the EPA underestimate the actual fuel and emissions savings made possible by start-stop systems. Lots of talk about the cycle being updated, but still no action... I work for a supplier very involved in this and it'll be on most vehicles, eventually, due to CAFE. Assuming, of course, that the test cycle...
     
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  3. Funny, typically start-stop systems such as was used on the 2007-09 Saturn Vue and Aura (as well as the 2008-10 Chevy Malibu) typically got poo-pooed here on Green Car Reports. Now that they've become "de rigueur" again I'm really not surpried this article failed to mention the 2012 Buick Regal and Lacrosse which utilize an impreoved versio of the GM BAS atart-stop system dubbed eAssist. Back to the Future? lol
     
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  4. @WopOntour: Actually, we've covered the 2012 Buick Lacrosse with eAssist several times on GCR, with a test drive in May:
    http://www.greencarreports.com/news/1057317_first-drive-2012-buick-lacrosse-37-mpg-eassist-prototype
    and an article just yesterday:
    http://www.greencarreports.com/news/1066700_2012-buick-lacrosse-eassist-tv-ad-sells-mpgs-avoids-h-word-video

    The problem with the first-generation BAS system was that it was considerably pricier for very little gas-mileage improvement over the Malibu once it was fitted with the 2.4-liter engine and six-speed automatic transmission. The improvement from the eAssist second-generation system is far greater.
     
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  5. Not really John.
    The first generation BAS systems also provided a min od ~15 improvement in city mpg over the same model with a 2.4l 4-cyl and 4 speed (4T40E).In fact, according to www.fueleconomy.gov MY 2009 Saturn Vue w/1st gen BAS has an improvement of 32% city (19 vs 25mpg) and 24% highway (26 vs 32mpg) making the combined economy improvement 27% (22 vs 28mpg) over the base 4cyl FWD version. (not much different from the eAssist Buicks)

    I also disagree with your statement of them being over-priced as they were at the time marketed and advertized as being the least expensive "hybrids" (abeit of the mild variety)available adding only approxilately $2000-3000 to the price of the car/SUV.Yet they continue to get no respect on sites like GCR
     
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  6. "Funny, typically start-stop systems such as was used on the 2007-09 Saturn Vue and Aura (as well as the 2008-10 Chevy Malibu) typically got poo-pooed here on Green Car Reports."

    The problem was that GM touted it as being equivalent to the Hybrid Synergy Drive, and then complained loudly when people looked at the MPG rating in the window (rather than the "hybrid" tag on the trunk), and decided not to buy it.

    The author the article is walking the line that was hammered out back then, advocating this as a low-cost technology to make conventional cars more efficient. She does not say that these systems replace an EV or a full hybrid, but she does say that it saves fuel.

    GM seemed to think that the "hybrid" badge was what sold the Prius...
     
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  7. You are totally incorrect.(and a typcial UCS-like response)

    GM never actually "touted" these products to be the equivalent of the HSD (or ANY "strong" hybrid for that matter) in any way shape or form. The marketed them just as they are now marketing the Buick system as in claiming an % of mpg imrovement over their own non-hybridized versions of the same product.

    Sure GM labled these hybrids BECAUSE THEY ARE. (By almost every metric that has been established to do so) It was only hybrid technology snobs like you that took exception.
    GM never claimed these sytems were anything more than what they were, a low-cost "mild" hybrid technology that demonstrated quantifiable results.

    If you can prove me wrong. Feel free
     
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  8. And, what do you expect to happen on the freeway when the line stops and every car with S/S delays the line moving again...right! even more time on the freeway. The place where it really shines is at traffic lights, not on freeways.
     
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  9. Actually, the start-rtop system doesnt delay the movement of cars in the slightest. The engine is commanded to start just as you release the brake pedal and it fires in an instasecond as it's being driven to ~750 rpm by a powerful electric motor (not a conventional starter) so their ZERO delay! (you cant even tell the ICE is stopping-starting in traffic if it wasnt for the gages)
    WOT
     
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  10. If you're driving with so little margin for error, then a fraction of a second's delay in getting power when you put the pedal down is the least of your problems.
     
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  11. Wop Ontour, I think you've managed to completely miss the point. The vehicles you mentioned had S/S only because they were hybrids. Until now, not one S/S system on any non-hybrid, limiting market share of S/S to about 2-4% of sales.
    Now, it's migrating to most vehicles, with market share expected to be over 50% by 2016, or one new car model away for most vehicles. That's a major change and by no means a "back to the future" scenario, as you claim.
    The claim that GCR has been anri-S/S is also a myth; GCR has simply reported that the current EPA mileage test cycles don't accurately portray the true savings and other reasons why S/S has been slower to grow that in Europe or Asia. Just my opinion, but I've never seen an anti-S/S bias.
     
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  12. I didnt miss the point at all. That is about all a mild or micro hybrid does, i.e. provide auto start-stop features This is because the electric power levels available from the energy source and motor is generally low so it cannot contribute significantly to propulsion. My wife's Saturn VUE has BAS and it is considered a "mild" hybrid. But the motor generator unit is only used at red-lights, stop signs once the engine is warm and perhaps a bit when accelerating hard (such as passing) so in the traditional sense of being a "hybrid" it is limited. Yet despite garnering some real measurable improvements in reducing idle emissions and mpg these systems were essentially ridiculed by "the hybrid community" and the outfits like UCS- rediculous!
     
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  13. I think it is the result of marketing arrogance by GM, not a problem with the technology itself.

    They tried to tell everyone that the BAS system was as good as the Prius's drive and that we should go out and buy GM because of the "hybrid" tag on the trunk, regardless of the mileage achieved by the vehicle. THAT is what started the ridicule. Because the BAS system really isn't equivalent to the HSD.

    (The Honda Civic Hybrid used a similar approach, but had the MPG numbers to be taken somewhat-seriously.)

    If they'd said "it's a normal car with a fuel-saving feature", I bet that the reaction of the green car community would have been far more favorable.
     
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  14. Again, I guarantee you certainly CANNOT link me to ANY GM advertising or propoganda that supports what you are claiming here.

    Just another blow-hard HSD snob IMO.
     
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  15. I would disagree that ALL mild hybrids were ridiculed. The specific challenge for the GM BAS system came with the 2008 Malibu fitted with the 2.4-liter engine + six-speed automatic. That car was rated at 22 mpg city, 32 mpg highway, for a combined rating of 25 mpg.

    The 2008 Malibu Hybrid with BAS was rated at 24 mpg city, the same 32 mpg highway, and 27 mpg overall--for a cost of $1,000 or more for what most buyers perceived as a negligible increase in fuel efficiency.

    Add to that the recall of the first 7,000 or so BAS installations in Saturns to rectify possible battery, along with "hybrid" marketing confusion, and the first-generation BAS system pretty much withered on the vine.
     
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  16. Sorry, that was meant to be "rectify possible battery leaking".
     
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  17. John, while what you are saying about the BAS Malibu's EPA rating is essentially true for 2008 it was in fact incorrect. GM eventually ammended the 2.4 BAS economy ratings the very next year to 26 city 34 highway (29 combined) yet nothing really changed. Agreed the Cobasys battery leakage issue was an unfortunate mitigating factor but generally something that was quickly and effectively remedied.

    Again, I want to reiterate that my statement above regarding the treatment of BAS (and similar technologies) was/is not something GCR directly propagated, more the hybid "community" (that often posts here).GCR merely reports the stories. But in the end what constitues a "hybrid" to most people is somewhat skewed from pure engineering definitions
     
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