Auto Start/Stop - Pros and Cons

scaredofdebt

I've just bought a Mini Clubman diesel with auto start stop, you can disable it and I am wondering what is the best option.

I'm wondering if the fuel savings it brings are worthwhile as there must be additional wear and tear on the engine with the extra starts. Also, I always thought starting an engine used more fuel than normal idling, so presumably you have to be stopped for a fair while for the fuel saving to be more than the additional fuel used to restart the engine.

My normal commute means the start/stop only comes on near the end of my 30 mile commute as the first 20 odd miles are country roads with no traffic or the motorway. Once I leave the motorway there's 2/3 sets of traffic lights that I usually have to stop at for 10-20 seconds or so.

Any comments welcome, especially if they are accurate!

DUTR

Well get your tree hugging suit on, it's not just about saving fuel, your'e reducing your emissions.
You don't have to disable the SS when you come to a brief stop, on my car you have to hold the brake for a couple of seconds for the engine to shut off.

WTFH

Some people insist on switching it off and tell you about all the fuel, damage etc that it causes. Others are slightly less in the Luddite camp and consider it a new technology that can save fuel.

My current car - which I've had for over three years now - is diesel and has stop/start. I don't disable it. The starter motor hasn't died, the battery is fine, and the stop/start only functions in certain circumstances. There is no risk of it not starting the engine, because it checks before it stops. I can accurately say that I have had no issues with it, nor have I read of actual owners having mechanical or electrical failures as a result of it. I can't comment on the amount of fuel used to restart the engine, as I can't measure it. I know my car is economical for its engine size, power and performance, but how much of that economy is down to stop/start, I can't say.

Ultrasonic

scaredofdebt wrote: »

I always thought starting an engine used more fuel than normal idling, so presumably you have to be stopped for a fair while for the fuel saving to be more than the additional fuel used to restart the engine.

For modern engines fuel injection is carefully controlled so that restarting doesn't use loads more fuel. If it did no-one would sell cars that did this. Note that this is different to the fact that cars use more fuel when just started from cold compared to when fully warmed up.

My normal commute means the start/stop only comes on near the end of my 30 mile commute as the first 20 odd miles are country roads with no traffic or the motorway. Once I leave the motorway there's 2/3 sets of traffic lights that I usually have to stop at for 10-20 seconds or so.

For that sort of trip the fuel savings will be small but so too will be any additional wear and tear. I understand your concern, but so far I've yet to read anywhere of mass starter-motor failures on cars with stop-start, so I'd be inclined to leave it switched on.

The OP does though rather beg the question, if you're reluctant to use stop-start, why did you buy a car with this feature? Models with this generally cost more don't they?

How old is the car? If new and under warranty you obviously have little to worry about.

It might be worth finding a Mini owners forum if you want to find out more about the particular stop-start system fitted to your car

Rodney_Trotter

WTFH wrote: »

Some people insist on switching it off and tell you about all the fuel, damage etc that it causes. Others are slightly less in the Luddite camp and consider it a new technology that can save fuel.

My current car - which I've had for over three years now - is diesel and has stop/start. I don't disable it. The starter motor hasn't died, the battery is fine, and the stop/start only functions in certain circumstances. There is no risk of it not starting the engine, because it checks before it stops. I can accurately say that I have had no issues with it, nor have I read of actual owners having mechanical or electrical failures as a result of it. I can't comment on the amount of fuel used to restart the engine, as I can't measure it. I know my car is economical for its engine size, power and performance, but how much of that economy is down to stop/start, I can't say.

Until it goes wrong. Yes it checks but the way you worded it makes it sound like it can never fail.

scaredofdebt

Thanks guys.

The car was 6 years old when I bought it so any premium for the start/stop feature is negligible, I didn't seek out the car for this feature.

Start/stop only happens if the engine is warmed up and the ambient temperature is above 4 degrees and if I am stopped in neutral.

I'll leave it on for now, fuel consumption is around 65 MPG so fairly happy with that.

Thanks.

Rodney_Trotter

scaredofdebt wrote: »

Thanks guys.

The car was 6 years old when I bought it so any premium for the start/stop feature is negligible, I didn't seek out the car for this feature.

Start/stop only happens if the engine is warmed up and the ambient temperature is above 4 degrees and if I am stopped in neutral.

I'll leave it on for now, fuel consumption is around 65 MPG so fairly happy with that.

Thanks.

Is that what you're actually getting?

scaredofdebt

Rodney_Trotter wrote: »

Is that what you're actually getting?

According to the App on my phone yes - it's a 40 litre tank and I'm getting around 575 miles to a tank so it's about right I think.

Only had it for a couple of tanks of fuel so I hope to do better when I know how to drive it properly, manufacturer quotes 67 MPG as average so there is room for improvement.

londonTiger

these are relatively new innovations, who knows how these cares will fare after 30K+ miles. Lots of stop starts in a diesel in the city - likely to be trouble.

scaredofdebt

It's got 83k on the clock so far and I don't do much town/city driving, so fingers crossed.

anotherbaldrick

The stop /start saves very little fuel and can be a total pain in a traffic crawl. I usually switch it off and only if I come to a holdup where I am going to be stationary for a minute or more do I activate it. On my car you can also restart the engine by a light twist on the steering wheel if you want to fire it up before you put your foot on the gas.