So, my wife’s 2005 Malibu Maxx reached the end of its serviceable life recently and we decided to replace it with a new (2015) Malibu. She’s loving the new car and I have to say I’m impressed (so far) by the quality and performance, especially considering it’s a 4 cylinder engine.
One feature has me scratching my head a bit though: the allegedly fuel-saving stop-start technology. Basically, when you’re at an extended stop (e.g.: a long stop light), and the all-knowing computer deems it safe, the engine stops running. Once you lift your foot off the brake (before even touching the gas pedal), the engine restarts and you can go about your day. This sounds like a good idea, and I’m sure it’s one of many creative tricks automakers will use to boost fuel economy numbers (I read that Ford will have this in ALL of their vehicles by 2017).
The problem is that it’s a well-known fact that most engine wear occurs in the first few moments after the engine starts. So, in the past, my wife’s car would be started (typically) 4 times a day (drive kid to school, drive to work, drive to get kid, drive home). Her commute includes 4 or 5 traffic lights where she’s likely to be sitting long enough for the engine to stop. Assuming traffic isn’t terrible, and there’s only one stop-start cycle at each of those lights, the engine is now “starting” 12 to 16 times a day; 3 to 4 times the wear and tear as before.
My suspicion is that this is a huge compromise. While the engine is idling, yeah, it’s burning gas without actually doing any work, but are we saving a few pennies, and preventing a bit of air pollution at the cost of needing a new starter every couple of years and an engine rebuild before it hits 100k? I feel like automakers should really be investing in alternative fuels or simply optimizing existing technologies rather than implementing these gimmicks that provide short-term gains at the expense of long-term consequences.
“The problem is that it’s a well-known fact that most engine wear occurs in the first few moments after the engine starts.”
Not necessarily “most”.
Since at startup the engine is not loaded and rpm’s are low most moving parts are not stressed so any wear is minimal.
The issue behind that claim is that after an engine has been sitting still for hours the lubricating oil can drain away from places where it’s needed.
Some of the extra startup wear is due to the engine being cold.
Not a problem with an engine that’s been off just a few minutes.
There is a one way valve (often in the oil filter) to keep the oil from draining out of the passages that distribute it throughout the engine.
That goes a long way to mitigate the problem; the time without oil pressure is very brief.
The starter is different than conventional, designed for the frequent use.
This is exactly “optimizing existing technologies” as you wished. It is a proven reduction in fuel consumption and pollution. With the electrification of most sub-systems including AC, it is completely practical. Some cars with this system allow it to be turned off if the driver desires. On a BMW, this must be chosen each time you start the car. Car makers also can “time” the engine stop so the engine is at the optimum rotational spot to re-fire in the quickest, most efficient way possible to reduce wear and tear on the started and annoyance to the driver.
It helps mpgs, and, since the engine is warm, it doesn’t really add to much to engine wear. It won’t do it with a cold engine, I believe. Let’s hope the starter system’s been adequately upgraded.
For years, we have been advised to turn off the engine when waiting at a railroad crossing. Unfortunately, the air conditioning is lost. On the modern systems with electrically driven air conditioning this doesn’t happen.
As far as undue wear on the starter, I would bet that the manufacturers have taken this into account. Unfortunately, lawn mower manufacturers did not take this into account when mowers came out with deadman controls that stop the engine when you let go of the handle. My wife,who has had 2 rotator cuff surgeries says having to pull the cord more often puts unnecessary extra wear on the starter–her.
I’ve noticed that UPS local delivery drivers now shut off the engines when making local home deliveries where they used to leave the engines running. I assume this must be company policy.
The engines are designed to do this, including the use of heavy duty starters.
Yeah, manufacturers are making many compromises to comply with uncompromising mandates from our federal regulatory agencies. You can send your letters of thanks to your state’s senators with copies to 1600 Pennsylvania Avenue. It won’t help, but sometimes it just feels good to unload.
I would absolutely turn that godawful device Off, and if it can’t be done I’d find a way to defeat it.
Also, I tied that stinkin auto-kill switch Off on my lawnmower before I even started it for the first time.
It’s cold starts that are harder on an engine, as mentioned above, not counting the starter wear.
As far as engine wear, I think you’re also forgetting that the engine wears less when it’s turned off than when it’s idling, although of course that’s by a minuscule amount.
It was built for that, plus I think the Malibu has two batteries one up front one in the trunk. I have it on my BMW and I have a button to disable it and i don’t have to push the button every time newer BMW’s are coded differently. It just annoyed me and don’t would never use it.
One of the main reasons there is so much wear on start up is that when you shut down a hot engine, the oil stops flowing, so the oil that is trapped in the head and the oil passages now have to absorb all the heat as the engine cools down. This very small amount of oil takes on a lot of heat and so it suffers some breakdown.
How much breakdown is determined by a number of factors. The two main factors are the length of the shut down and the wear and tear on the oil. Oil that has a lot of miles or hot shut downs has a lot of the broken down oil mixed in the oil pan and it suffers more at shutdown. Fresh oil has a lot of life in it before the breakdown becomes more critical.
A cold restart with only the more broken down oil in the passages and on the wear surfaces causes the wear. But with the short shutdowns at a red light, the oil does not have time to breakdown significantly, even oil that is close to the next oil change, so the start up wear is not significant either.
My son rented a Malibu with this feature, and it worked great. Very seamless, at least it seemed to me.
Modern cars start very quickly. Even my 2011 Cruze, with 127,000 on the clock. Still, to this day, twist the key to start then let it go. It’s running. Really. It starts that fast.
As mentioned above it is cold starts that cause engine wear. We looked at a 15 mailbu, ended up with a KIA, but in case you do not know @cvkealey you have 2 batteries, one for the starter motor and one for everything else.
I rented a 2015 Malibu recently and had driven it for a day before I realized it was shutting off at every stop. It was seamless and practically unnoticeable. I was very impressed.
Poor lubrication during cold starts is what causes a lot of engine wear. After a few minutes, the car warms up. Then you have warm starts and the oil flows much better. European manufacturers have been using stop/start technology for quite a while. I had a BMW 128d rental in 2010 while on a business trip in Europe. It took me a while to get used to the auto stop/start, but after a few days I did. Expect the auto manufacturers to use every trick they can to increase fuel mileage to meet the new CAFE regulations.
I don’t think it causes any add’l engine wear, but it does present a potential reliability concern if the method used to start the car isn’t robust enough to handle the number of starts being required, year in and year out. It’s another thing that could go wrong and strand the owner at the grocery store in a rain storm in other words.
There is extra stress on the battery as well, I’m sure. If you poke around the manual, there’s likely a way to disable the stop/start feature so it idles like a ‘normal’ car if so desired.
You will never notice the effect of engine wear on those warm restarts. As others have noted, it’s restarting a cold engine that adds more wear.
But with today’s engines being so reliable, seeing engines suffer wear from excessive cold starts is difficult to find. I like the analogy some have used on this board, which is your engine might last 310K miles instead of 315K miles.
The entire starting system has been redesigned to accomplish this…Engine lubrication is not an issue, everything is wet with oil, the only “dry start” is the first one in the morning…