There’s no perfect data on it, no, but common sense tells us if it was happening with any frequency it would be newsworthy. And experience tells us modern cars very rarely fail to start in the first place. There is also not that many points of failure. Certainly not more than that the system can be thoroughly tested for its behavior in those cases.
It’s always possible to worry about “what if?”. Sometimes it’s meaningful, like if you’re considering taking a nap while on auto-pilot in your Tesla. Sometimes it’s meaningless, like if you don’t leave your house because the odds of being harmed by a meteorite impact is smaller indoors.
Driving any car includes a risk of getting killed in an accident, or getting stranded in the middle of an intersection because of car trouble. There is no data indicating having a car with a start/stop-system increases those risks noticeably and good reason to think the increased risks are negligible.
And automakers are looking at ways to shave 1/10 of a mpg for EPA testing, so even if it is less then european standards, start stop is significant on the tests.
I think this feature is the result of thinking about one metric while neglecting others. In this case the fuel efficiency of the car is being improved at the cost of engine life / maintenance costs.
There are other examples from other spheres too :
Toilet flushes with lower volume of water to be more environmentally friendly (people flush two or three times though so it sort of defeats the purpose)
Capacitors for motors (start/run) have vegetable oil to be more environmentally friendly. But their life has significantly gone down. If you have a AC bought in the last 10 years or so, you may have replaced the capacitors.
Detergents for laundry and dishwashers are phosphate free. I have not seen much difference but I’ve heard people say it takes longer or more washes with the new zeolites.
Ceiling fan fittings modified to accommodate only small bulbs to be more environmentally friendly. I have seen people fit them with adaptors and regular light bulbs
Well, it is extended, because engine runs fewer hours and should have less heat soak.
Engine wear is highest when starting a **cold ** engine (and only the initial cold start – not subsequent ones, say 2, 3 or several minutes later). Why the initial cold start is worst: Oil is slower, parts don’t fit right, combustion isn’t optimized yet. Thermal expansion/contraction is a cycle that weakens metal ever so slightly, too.
Shutting down a warm engine and restarting it removes some wear by reducing operating hours per mile.
Any good rotating equipment reliability book will be filled with citations. In fact many rotating equipment have built in triggers for maintenance based on how many start / stop cycles it has been through. Here are some references for rotating equipment in general
1> For Pumps : The most rigorous and stress-inducing time for a pump is at start-up. This places significant strain on the pump in various areas. Most notably, seals and bearings are prone to failures due to frequent starts. **Therefore, stops and starts increase the risk of failure. ** cite : Reliability | Duty versus standby | Plant Services | Plant Services
2> For Hard Dives : when a disk is younger and has had fewer start-stop cycles, it has a better chance of surviving the next startup than an older, higher-mileage disk … For example, the Seagate Barracuda 7200.10 series of desktop hard disk drives are rated to 50,000 start–stop cycles
3> Gas Turbines : Turbine trauma: the risk of the start-stop cycle News - Power Engineering International
I can go on and on for all types of rotating equipment. The stresses on any rotating equipment for start-stop will lead to increased degradation. Maybe you can give an cite why this is not true for gasoline engines ?
All of your examples are for equipment that have a narrow range of speed during operation. Gasoline engines are designed to function at a wide speed range. When starting from hot there’s not that much difference between starting from 0 and revving from idle.
Not true - Reciprocating Engines work at wide speed range. And there is a huge difference - the battery needs to deliver the power in second case and Low cycle fatigue is an universal phenomenon.
I do not own a Start-stop car , but my friend owns a Subaru which does. Per her, Subaru does not cover the stop/start battery/alternator under its powertrain warranty. Ordinary cars are designed for something like 50,000 start/stops - when we are talking about 500,000 start/stops now.
If it makes you feel any better, I’ve driven a hybrid Ford Fusion since 2013 with this feature. (Even more so, since a hybrid won’t just turn off at intersections, but also any time the electric drive can take over.) Never once has it failed to start. In fact, so far it’s been by far the most reliable car I’ve ever owned, despite the engine being far more complicated than the older cars I drove.
My Fusion will do full-electric drive at freeway speeds. (72 MPH is the cap on it, or so the dealer told me when I bought it.) (Just to brag a bit.)
It would be relevant to ‘wear’ (not just engine wear) if the battery, alternator, starter wore out more quickly. However the starting assumption of some on the Luddite side of this question seems to be that car makers wouldn’t modify the design of those components for start-stop, but obviously they do. Do they do so enough to get the same life as in non-start-stop cars? Maybe or maybe not. And as was pointed out, under the anti-Luddite assumption the systems are (properly) designed to last just as long as non start stop cars, the components must be more robust and complicated and therefore more expensive to replace. Whether that’s significant in the big picture though is another question.
But I agree sticking just to the engine itself there’s no reason to think its life would be shortened by being part of a start-stop system with all the software checks the current cars have not to stop/start when the engine’s not warmed up enough, when it’s extremely cold outside, an arm’s length list of things I think was linked for one brand of car last time this came up. Some people ‘hyper mile’ by simply turning off their non-stop start cars at every stoplight. That’s not what the built-in systems do.
I like the system, car is perfectly quiet when stopped, and as was mentioned it has a non-negligible impact on fuel economy in real life ‘city’ conditions.
Is there any “Cost of ownership” data available for the Auto Start/Stop cars compared to traditional cars ? Since this technology is old enough, this should be readily available but I didn’t have any luck on the Internet.
The engine is usually about the last piece of equipment to fail on a car. Either the transmission goes out, or else people feel that they’re being nickled and dimed to death by smaller repairs. Of all the reasons why people decide to scrap a car, engine failure is very close to the bottom of the list.
Your concern is utterly irrelevant for all but a handful of very unlucky people.
I’ve got a naive question about these “stop/start” cars. Do they stop the engine every time the car stops? Let’s say you are in a long line at a tollbooth. Does the engine stop and start every 5 seconds as you stop-and-go inches at a time?
I did a very cursory Google for this but couldn’t find the info.
NOBODY covers things like starter, battery, or alternator under the powertrain warranty.
No, your OP did not. it was FUD, and you haven’t provided any cites for your claims so I wouldn’t be so eager to demand cites from others. Talking about ceiling fans, hard drives, and washers is not a cite.
as I’ve already pointed out, the notion that starting a car’s engine is hard on it is true in the context of a COLD ENGINE. when the engine is cold, these things are true:
practically all of the lubricating oil has collected in the sump, leaving a bare thin film on moving parts,
the oil has higher viscosity when cold and will take a non-zero amount of time to pump up to all of the parts needing lubrication,
the moving parts have greater clearances between each other because thermal expansion has not occurred yet,
the engine is operating with an enriched fuel:air mixture to run acceptably which means unburned fuel is left behind; some of which works its way past the piston rings and into the oil.
when you restart a hot engine after a minute of so or sitting, none of those things are true. a hot restart is nothing. the moving parts are all still adequately lubricated; the oil galleys are still full, and the fuel:air mixture needs no enrichment. And as I mentioned above, the engine only has to crank briefly because the PCM is still aware of the relative position of the crankshaft and camshaft(s.)
No. an auto stop will not take place under certain conditions, including but not limited to:
the engine is not up to normal operating temperature
the climate control system will not be able to maintain the user’s set temperature
the engine has been off for long enough the catalyst may cool down too much
the driver is in stop-and-go traffic and the engine has already done several stop-start cycles over the past (x) time interval
and others I’m likely not thinking of.
edit: #4 in that list would apply to your toll booth example. in the cars I’ve driven with it, I think it was 3 or so auto stop/start activations within a couple of minutes would disable AS/S until after the engine had been running constantly for a certain amount of time after.
First of all, when a new technology is introduced the onus is on the introducer to explain its effects on reliability, maintenance costs, safety, etc. Its not for the reluctant buyer (like me) to provide cites for the downside.
Here are the possible downsides:
Up until about 2007, auto Start/Stop was only available for manual cars. It was (and still is) difficult to integrate with automatic transmission. The new technology has to put the car in neutral somehow every time it stops. It’s not trivial to do so and the reliability of the new system is as yet in established.
For hotter places, turning the Car off effectively turns the AC off too unless some other logic is incorporated.
The starters used in traditional cars have been same for the last 100 years or so and have proven reliability. The new starters - (Permanently engaged) are totally different and have not yet proven their reliability.
Engine vibration is always there when the engine starts or stops - whether cold or hot. This is discomfort for many people like me.
Although you are right that there is an oil film when it has been off a few seconds, the oil is still not under pressure. There is a lot of research on developing new crankshaft bearings that can withstand the order of magnitude increase in start/stop, their reliability is still not established.
Almost all manufacturers I have seen classify the Start/Stop system under emissions control equipment and not under mechanical components and thereby the warranty terms are different.