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The 2000 Volkswagen Lupo used start-stop to achieve a fuel economy of 75 mpg in Europe on a diesel engine. Manufacturers haven't brought the tech to non-hybrids in the U.S., due to flaws in the EPA's fuel economy testing.  (Source: Cars Plus Plus)
EPA is finally considering looking at the real value of stop start

Fuel economy ratings are supposed to provide an estimate of the vehicles' real-world performance, helping customers determine how efficient the vehicle is.  Unfortunately, the ratings are only as good as the tests that determine them, and in the U.S. Environmental Protection Agency's case, those tests aren't very good.

One significant oversight is stop start technology.  Overseas stop-start technology is featured on a host of models, including the Audi A3 TDI, BMW 1-Series, BMW 3-Series, Mazda 2, Mini Cooper, Toyota Yaris.  The technology is somewhat expensive -- it's about $500 extra to install -- however, it's more than worth it, providing fuel economy gains of around 7 percent.

The EPA's flawed test cycle, though, currently only includes one stop so the tech only earns automakers a 0.1 or 0.2 mpg increase in the official EPA mileage estimates, despite much larger real world gains.  Without the extra rating to justify the extra costs, manufacturers simply haven't been importing the tech on U.S. models. 

Currently, the only vehicles to feature the tech are hybrids such as the Toyota Prius, Honda Insight, Chevrolet Malibu Hybrid and BMW ActiveHybrid X6, as their electric systems allow the tech to be implemented at a much lower costs.  The net result is that at the end of the day, the U.S. is trailing the rest of the world in fuel economy.

Still the allure of models like the Volkswagen Lupo, which received an estimated 75 mpg, keep customers demanding that the EPA reconsider stop-start.  Robert Davis, Mazda's top product-development executive in North America, comments, "In Japan, we're seeing anywhere from 7 to 9 percent fuel economy gains from it. That's a jump from 33 to 37 miles per gallon in a metro environment."

Audi of America spokesman Christian Bokich complains, "We did not realize any savings in U.S. EPA estimates based on required testing cycles."

The EPA may finally be coming around and may try to fix its flawed test procedure.  It's taking public comment on stop-start technologies, currently, and will look to announce new procedures in April.  Those procedures could finally include a test with more stops.  Mazda is urging automakers to join together to lobby the EPA to give stop-start its just rewards.  While this is obviously a matter of personal interest to the company, it's also important industry wide, and to U.S. consumers.

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Issues i see
By FITCamaro on 12/30/2009 11:43:07 AM , Rating: 5
While I am not trying to deny the fuel economy benefits, there are more things to think about.

The majority of the wear on a car's engine is at startup. So by having the enigine stop at every light, you are drastically increasing that kind of wear on the motor.

Another thing not being looked at here is how people drive in Europe vs. the US. In Europe people come to a complete stop less than here. They have more roundabouts instead of stop lights than we do.

I personally wouldn't want my GTO shutting off at every light. In the end it'd just mean more and higher maintenance costs.

RE: Issues i see
By corduroygt on 12/30/2009 12:11:19 PM , Rating: 4
Wear is bad at cold startup in the morning when the car has been off all night and all the oil went down to the crankcase, but when the car is warm, stopping the engine between 1-120 seconds won't do harm. Any stop start system would have to be monitoring the oil temperature and not go into effect if it's too cold.

RE: Issues i see
By Spuke on 12/30/2009 2:02:41 PM , Rating: 3
but when the car is warm, stopping the engine between 1-120 seconds won't do harm.
How so? Please explain.

RE: Issues i see
By Alexvrb on 12/30/2009 7:30:54 PM , Rating: 2
A good stop-start system will avoid turning the engine off when it hasn't yet reached operating temperature. But there could still be slightly increased wear when the oil is given a minute or two to drain. I'd say its generally a non-issue.

However, there are other problems with stop-start on a non-hybrid vehicle. Even half a second of delay (and that's if everything works perfectly) would drive me up a wall, especially in stop and go traffic. But I'll let that one pass, since we'll call it user preference. What about the starting system, what modifications do they make compared to a traditional starter motor -> flywheel/flexplate setup? Then there's your accessories and other components:

- Blower motor - does the blower motor stop working? Or continue to run off the battery(ies), providing you with heat and maybe even marginal A/C.
- Rear defroster - I bet that shuts off, its a power hog.
- Radiator/condenser fan(s) - I'd say these typically shut off - but even if its hot and the heat from the exhaust manifold(s) continues to bleed into your engine?
- Water pump - electric water pump? Why not, while we're saving a few % with a stop-start system. This will save a few more.
- A/C compressor, are they going to install a 12V electric compressor, and if so do you think a 12V compressor will be USEFUL compared to the high voltage units they put on a typical hybrid? Or just stick with a belt driven unit and have it shut off.
- Most important of all - How well will your standard non-deep-cycle 12V automotive battery going to handle all this? Maybe they'll throw in a auxilary battery or two, and a bigger alternator, or maybe they'll make it a 24V system. Two deep cycle BCI group 31 batteries, that's the ticket.

There are issues with stop-start on non-hybrids, and the cost of the stop-start system alone does not fix them. So a vehicle with a stop-start system that does NOT suffer from the above problems will certainly carry a premium above the $500 mark.

RE: Issues i see
By Alexstarfire on 12/30/2009 8:03:17 PM , Rating: 2
I would imagine the fans and water pump would be all electric. There is no reason for them not to be. Not sure about the rear defrost, but I don't think 30 seconds of not having rear defrost is going to be a big deal. Not like it provides heat for you. The AC compressor I'd imagine will be just like normal ones, so not electrical. That'd make a huge strain on the battery and would probably be pretty crappy at it as well.

And no, no way they'd provide extra batteries. They might, however, put in a slightly larger car battery, but I don't see any reason for them to without putting either rear defrost or an electric AC compressor in there.

RE: Issues i see
By lucyfek on 12/30/2009 8:13:18 PM , Rating: 2
well, i don't have a fancy car so my stop-start system if fully manual. i shut the engine off at lights (or even before, no stupid auto-transmission in my car either) and start when lights are about to turn green (radar detector is good for predicting this - if you can't see lights/traffic, with some experience you get of the intersection ahead of others). so far so good and i believe this actually reduces engine wear. and i would especially shut off engine when not fully warmed up - modern cars guzzle until they get warm (and wear engine at high rpm to get there) and i don't feel like paying for not moving. if you're concerned with engine wear when cold get full synthetic 0w the next time you change oil - well forth the extra few $.

RE: Issues i see
By Spuke on 12/31/2009 12:39:57 PM , Rating: 2
if you're concerned with engine wear when cold get full synthetic 0w the next time you change oil - well forth the extra few $.
Cold start wear has everything to do with oil flow. Think about it.

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