Cars With "Stop-Start" Technology

My latest Audi has that. I doubt if they would be fitting such systems if they were going to damage the car. It can be a little annoying if it cuts for two or three seconds before you need to move but other than that it works perfectly.

I doubt if the Herald would go for 30000 km between oil changes.

I used to use it (BMW 123d) but now the car is out of warranty i disable it. Car tends to protect itself and disengages the start / stop if the battery voltage is too low, outside temperature too low, coolant temp low etc etc. The amount of difference it makes on my usual journeys makes it a bit of a pointless addition and whilst i'm sure the system and engine will last the lifetime of the car i'd prefer to not to pay the bill if it does go wrong 

I use it (BMW with auto)  but I use it combined with some road reading:  If I'm approaching stopped traffic & its liable to move off or  traffic lights liable to change in a few moments,  then I flick the gear change over from D to DS & the engine stays running.  

We've got it in a Merc & BMW, both autos. It seems to work OK but I really question how much fuel it actually saves. A few second's stop at traffic lights and then the battery has to kick in to restart. I usually switch the blessed thing off if I remember and anyway it's inoperative in the Sports modes.

.......  next to bugger-all I'd say. Might save a tenner on fuel over X years,  but what price for a worn out starter.    Might be more of a marketing gimmick if truth be told,  or pandering to the green party (bless-em)   

It's not just about fuel saving

https://en.wikipedia.org/wiki/Idle_reduction

I have it in my Mercedes C-class.  I tried to get used to it but like others find it irritating when the engine cuts out when the car stops for only a few seconds. I would worry about the additional strain on the starter motor.  Fortunately there is a handy button on the dash which deactivates the thing with a single push so I tend to turn the system off as soon as I get in the car and then activate it when I know my 'stop' is going to last a minute or two e.g. at traffic lights. This seems to work fine but I know it can be more tiresome in some other cars. I recall hiring a VW Passat a year or two ago which had the feature but to deactivate it you had to go through a complicated menu. And of course the default position is 'on' so turning off each time was a real chore.  So in summary I choose when the engine cuts out, not the car.

Mike

Mike, I too have a Mercedes [A class] and find most of the "tech stuff" irritating and unnecessary.

Regards Graham. 

Interestingly,  regarding starter life with these start-stop cars

Many moons ago in the 1980's my old company developed an auto-stop/start system.

The company make transport refrigeration equipment & the diesel powered units can be run almost continuously 24/7/365 maintaining temperature.  But running heat-cool-heat-cool for hour after hour to maintain a +/-1'c temperature can be done much economically by stopping the engine & letting the container box temp climb a degree or so & then restarting the engine.

Our engine supplier(s) were not at all happy,  one even conditionally withdrew warranty on the starter.

But over the next 10 years, we found our warranty costs for starters reduced by a significant amount.   The cost & failure rate measured over the warranty period was massive;  but interestingly failure per running hour was also lower. We concluded that starters benefited from the 2 or 3 times an hour exercise,

I am not saying this transposes into start/stop cars tho',  but starter life might not be an issue.  

Yes, Graham. Given the choice I'd be happy to dispense with rain-sensitive wipers and auto-headlights.  I feel I'm perfectly capable of operating those functions when they are needed.  

Mike 

You make a good point, Mike B.  I believe the advice is to leave on air-con systems, because lack of use is more likely to lead to failure. Cars generally run better when used regularly. And classic cars often suffer mechanical problems if shut away in a garage for long periods and used too little.  

With regards to air con, I try and switch mine off for the last few miles of longer journeys to help prevent moisture forming which then 'might' encourage nasty smells. 

Correct,  a stationary compressor seal can dry out & as a result it looses its sealing ability & leaks refrigerant gas.  Running a compressor with no gas will reduce it to a pile of small ground up peieces in about 10 minutes.

Even if you car has a "auto" climate control,  don't trust it to run the compressor during the winter.  In the winter months I change my thermostat to minimum when the car interior is warm,  & make sure its pumping cold,  probably once or twice once a month.  It only needs the compressor to rotate a few seconds to re-wet the seal.  

My Volvo V40 has auto stop/start, but has an inhibit button on the dash. It can be irritating when stood for only a few seconds. I try to anticipate the standing time and keep it in gear if necessary.

Regarding the air/con. I switch it on, if only for a few minutes, each journey even in winter. Not using it for extended periods leads to seals drying out and eventually leaking coolant.

And what if you auto A/C is running?  You certainly shouldn't start your engine with the clutch for the A/C engaged, so it seems a bit silly to have to disengage, re-engage, etc. even if done by computer.

Then there is the issue of the fact that the A/C won't cool while the engine is off.  The reason I turn A/C on is because I am hot, and I don't want to be.  (I honestly don't know how I lived in Dallas for all those years, and now I may have to relocate to Houston for work...ugh.)

But I see this as a gimmick more than a practical situation - until we can eliminate the use of fossil fuels it's all just tilting at windmills, IMHO.

It isn't engaged,  all the cars I know engage the A/C clutch on alternator charge or engine RPM sensor.

Besides an engaged AC compressor is not a load that affects the starter.

When ambient temps fall to about 4c your air con won't work anyway, it protects itself from freezing up.

Not always so Tony,  auto climate systems run the compressor:  some have a system that runs them for a short time at start up just to wet the seal irrespective of temperature,  others have a dehumidification function that uses the compressor to dry the air,  if the auto system needs more cool than it can get from outside air, such as during air recirculation, then it runs the compressor.

If the gas leaks there will be no pressure in the system. Compressor won't start if the pressure's too low.

Switching off the engine should be a legal requirement in congested city centres, walking around London during the rush hour is not a pleasant experience.

In Copenhagen I don’t thing your allowed to idle for more than a minute.

Only if they have LP sensing  ..........  & with basic AC as opposed to climate control,  is more than likely they don't.

The other affect is that with low (as opposed to "no") refrigerant, the low gas flow does not return compressor oil effectively & it pools in the evaporator.  Whatever no gas & no oil is is the primary cause of all compressor failures.

I love it - it feels weird and wrong driving cars without it now.

Well, my car has a very basic A/C and the compressor stopped working when the refrigerant leaked out.

Even the most basic A/C systems will have a pressure switch.