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    Rising petrol prices... would you ?

    turn off your car whilst waiting at a red light to save money, something was said about it on the mse e-mail I got as a way to save money on fuel bills.

    I personally though it seemed a little silly, can you imagine in the middle of a city on rush hour taking a few seconds longer to move, hello road rage! but seriously wouldnt it use more to start it than to be idiling for a few minutes. In the place I live the light tend not to stay on for very long so by the time you start the car then move, the lights would be red again! seems mad

    33 Comments

    Slow down i drive a 2.2 but still only do 65 to work i now get 55 mpg.

    i wouldnt takes people long enough to move at lights

    have you ever noticed when your in a que at lights you dont even move until the lights have went to red again if everyone was just ready to move would speed things up a bit

    I think it would come down to if you really knew the sequence/time length for the set of lights - eg, if it was a cross-roads and you've just pulled up to a light turning red and you knew you were going to be there a minute or two.

    Personally, I'm glad I've sold my car and now biking and walking to work. I can't see petrol price increases slowing down just yet...

    well.. bmw and mini have this new stop/start engine which when u stop temporarily, like at the light, the engine goes off but once u put it in gear and ur clutch in again it switches on again..

    so i must think its a gud idea.. as i own a mini and get around 65mpg

    Original Poster

    meandog101;8128946

    I think it would come down to if you really knew the sequence/time length … I think it would come down to if you really knew the sequence/time length for the set of lights - eg, if it was a cross-roads and you've just pulled up to a light turning red and you knew you were going to be there a minute or two.Personally, I'm glad I've sold my car and now biking and walking to work. I can't see petrol price increases slowing down just yet...



    lucky you:thumbsup: not really practical for me to get rid of the car unfortunately, cant imagine walking my 5 4 &3 yr olds about the place, we used to be fine without one, used the bus to get to work or wherever not so easy with the kids though we did try it for about 2 months ofter I had my third, but it was just too stressful and time consuming so we got another car

    Original Poster

    red_one;8129046

    well.. bmw and mini have this new stop/start engine which when u stop … well.. bmw and mini have this new stop/start engine which when u stop temporarily, like at the light, the engine goes off but once u put it in gear and ur clutch in again it switches on again..so i must think its a gud idea.. as i own a mini and get around 65mpg



    now that is a good idea if the car did it automatically, cool, I have a citreon c8 usually I get about 35 mpg but its a big car, its a diesel as well

    The exact figures will vary from car to car but most cars will use much more power starting the engine that having it idle for a few seconds. When you start a huge amount of energy (from both battery and petrol) is needed to crank the engine and get the fly-wheel up to speed, plus a significant amount of inefficiently burnt fuel is wasted in the process. If you are stationary in a traffic jam it might be a good idea to switch off, but for just waiting at the lights I'd be surprised...

    red_one;8129046

    well.. bmw and mini have this new stop/start engine which when u stop … well.. bmw and mini have this new stop/start engine which when u stop temporarily, like at the light, the engine goes off but once u put it in gear and ur clutch in again it switches on again..so i must think its a gud idea.. as i own a mini and get around 65mpg



    They don't work the same as traditional starter-motor:engine:alternator combinations though. Often they have a redesigned combined alternator\starter-motor that is normally inactive, charges the battery during deceleration and reverses to start the engine when pulling away; conventional starters and batteries aren't designed for such a cyclic process...

    jah128;8129078

    The exact figures will vary from car to car but most cars will use much … The exact figures will vary from car to car but most cars will use much more power starting the engine that having it idle for a few seconds. When you start a huge amount of energy (from both battery and petrol) is needed to crank the engine and get the fly-wheel up to speed, plus a significant amount of inefficiently burnt fuel is wasted in the process. If you are stationary in a traffic jam it might be a good idea to switch off, but for just waiting at the lights I'd be surprised...They don't work the same as traditional starter-motor:engine:alternator combinations though. Often they have a redesigned combined alternator\starter-motor that is normally inactive, charges the battery during deceleration and reverses to start the engine when pulling away; conventional starters and batteries aren't designed for such a cyclic process...



    ^^^ just about sums it up well.

    You can save much more by improving your driving technique.

    I wouldnt. Ive got a Corsa Diesel. Getting 53mpg the now as well! Happy days.

    Banned

    If you stopped your car at lights, you would use more fuel restarting.

    Plus, you'd look a bit of a tit.

    Banned

    vibeone;8129455

    If you stopped your car at lights, you would use more fuel … If you stopped your car at lights, you would use more fuel restarting.Plus, you'd look a bit of a tit.



    absolute rubbish modern engines dont work like that anymore there not sitting there turning over for ages trying to start

    •Turning the engine off will normally save petrol provided the engine does not require choke to restart it, and provided it starts easily without wasting unburnt petrol while turning over on the starter. The idea that turning off briefly and restarting wastes petrol probably comes from the fact that cold starts involving the choke do use more petrol.


    Ten seconds of idling can use more fuel than turning off the engine and restarting it. If you’re stopped for more than 10 seconds – except in traffic – turn off the engine

    Banned

    fragaliciousbob;8129485

    absolute rubbish modern engines dont work like that anymore there not … absolute rubbish modern engines dont work like that anymore there not sitting there turning over for ages trying to start •Turning the engine off will normally save petrol provided the engine does not require choke to restart it, and provided it starts easily without wasting unburnt petrol while turning over on the starter. The idea that turning off briefly and restarting wastes petrol probably comes from the fact that cold starts involving the choke do use more petrol.Ten seconds of idling can use more fuel than turning off the engine and restarting it. If you’re stopped for more than 10 seconds – except in traffic – turn off the engine



    You have a habit of accusing people of talking rubbish don't you.

    I have read your post, and simply disagree, so therefore I state YOU are talking rubbish. Sorry about that.

    Banned

    vibeone;8129512

    You have a habit of accusing people of talking rubbish don't you.I have … You have a habit of accusing people of talking rubbish don't you.I have read your post, and simply disagree, so therefore I state YOU are talking rubbish. Sorry about that.



    i'm not accusing you i'm telling you , get your facts straight and you'll not look like (how did you put it ) a bit of a tit

    Banned

    fragaliciousbob;8129535

    i'm not accusing you i'm telling you , get your facts straight and you'll … i'm not accusing you i'm telling you , get your facts straight and you'll not look like (how did you put it ) a bit of a tit



    My facts are straight cheers - you are talking out of your backside, modern cars, old cars, I didn't specify, but I am now - it makes very little difference.

    And btw, I'm TELLING you.

    Arrogance is outstanding, especially when wrong.

    Banned

    Starting an Engine Consumes More Energy Than Running it
    There is a widespread belief that starting an internal combustion engines consumes more energy that when it is running. Most of the time, this belief is false. Those who hold this belief will be found to idle their engines for long periods, wasting fuel and producing emissions needlessly.

    How did This Myth Come About?
    Many years ago, cars (automobiles) had a manual choke for starting a cold engine. This was usually on a pull button or a lever. Its purpose was to make the combustion mixture richer in fuel in order to make starting easier. As this was a manual process, some skill would be needed to only use as much choke as necessary to produce a quick start of the internal combustion engine.

    If insufficient choke was applied, the air and fuel mixture would not burn. The air and unburned fuel would leave the engine and enter the atmosphere via the exhaust pipe. Thus, the energy giving effect of the fuel will have been completely wasted.

    Similarly, if to much choke was applied, the air and fuel mixture would burn erratically. Sometimes, the fuel would condense in the cold engine resulting in a condition known as a flooded engine. To overcome the problem of a flooded engine, the choke would have to be turned off and the engine turned over many times to flush the fuel from the engine's cylinders. Then another attempt to start the engine with the choke could be made. Whenever the engine was not starting, air and unburned fuel would leave the engine and enter the atmosphere via the exhaust pipe. Thus, the energy giving effect of the fuel will have been completely wasted. In the case of an engine that started with too much choke, some of the fuel would not have been burnt and this fuel would leave the engine and enter the atmosphere via the exhaust pipe.

    Getting the choke setting right is a skill. Without that skill, fuel is wasted and this may have been the source of the myth that starting an internal combustion engines consumes more energy that when it is running.

    With manual chokes there is a reasonable likelihood that fuel will be wasted when starting a car. Nowadays, cars have automatic chokes fuel is used more efficiently with less waste.

    Crushing the Myth
    When starting an engine without any choke and without any throttle, the rate of fuel usage is no more than an idling engine. When a modern engine is warm, there is no need to start an engine with choke or throttle. To use choke or throttle with a warm engine is a bad practice as it is unnecessary.

    When starting a cold engine with the choke, the rate of fuel usage is more than an idling engine. However, the choke should be reduced immediately after starting and will be switched off completely after a minute or two. With an automatic choke the reduction and switching off is done as quickly as possible. With a manual choke it is likely that it the choke will not be reduced as quickly as an automatic choke but, using good practice, will be switched off after a minute or two of starting the engine.

    So, leaving an engine to idle for more than a minute will use far more fuel than switching the engine off for over a minute before restarting it.

    Of course, some energy will be used by the starter motor to restart the engine and there will be more wear and tear on the starter motor and battery, but these are insufficient to the fuel wasted by an engine idling for more than a minute.

    What is also very bad for the environment is to have an engine idling with the air conditioning on. Air conditioning requires far more fuel to keep the engine idling than is required for an unloaded engine.


    environment-watch.co.uk/env…htm

    Banned

    Moral: Don't believe what you read on the internet.

    Cheers for clearing that up. You are still wrong.

    Banned

    vibeone;8129643

    Moral: Don't believe what you read on the internet.Cheers for clearing … Moral: Don't believe what you read on the internet.Cheers for clearing that up. You are still wrong.



    so based on the above quote i'm right thanks for that

    Banned

    vibeone;8129559

    My facts are straight cheers - you are talking out of your backside, … My facts are straight cheers - you are talking out of your backside, modern cars, old cars, I didn't specify, but I am now - it makes very little difference.And btw, I'm TELLING you.[SIZE="6"]Arrogance is outstanding, especially when wrong[/SIZE].



    :lol: irony(note:correct usage)

    i believe the internet term is "pwned"

    yet again too much jibber jabber and not enough facts, nowt new

    glad i dont have a car at the moment!

    fragaliciousbob;8129656

    so based on the above quote i'm right thanks for that


    HI BOB!:thumbsup::)

    Banned

    raptorcigs;8129721

    HI BOB!:thumbsup::)



    long time no see bud hows things

    HEY BOB WHO DOSE THIS REMIND YOU OF BUD
    http://riverdaughter.files.wordpress.com/2009/07/head-up-ass.jpg

    Im Good Bob Hope Your Ok

    Banned

    raptorcigs;8129736

    HEY BOB WHO DOSE THIS REMIND YOU OF BUD



    there are a couple of members this could apply to matey they know who they are all they try and do is use their smart mouths personally i'm not impressed lol

    glad your good

    Banned

    fragaliciousbob;8129656

    so based on the above quote i'm right thanks for that



    No, you are wrong, as stated in my first post.

    Like I said - you need to stop believing what you read on the internet, because you are very wrong.

    But do keep stopping your car at lights lol.

    Thread = pwnage free thread.

    VB1

    The way i see it is your wasting more fuel starting the car again then letting it idle in traffic. Yeah i now someone has already disagreed on the first page but thats my opinion i am allowed to have one aren't i? then again this is hotukdeals and you normally get slated for having a opinion.

    Banned

    Borat;8129797

    The way i see it is your wasting more fuel starting the car again then … The way i see it is your wasting more fuel starting the car again then letting it idle in traffic. Yeah i now someone has already disagreed on the first page but thats my opinion i am allowed to have one aren't i? then again this is hotukdeals and you normally get slated for having a opinion.



    You will be "told" you are wrong.

    Just ignore him - some people!

    Borat;8129797

    The way i see it is your wasting more fuel starting the car again then … The way i see it is your wasting more fuel starting the car again then letting it idle in traffic. Yeah i now someone has already disagreed on the first page but thats my opinion i am allowed to have one aren't i? then again this is hotukdeals and you normally get slated for having a opinion.


    depends upon the time stopped

    Whether it saves a minute drop of fuel or not I wouldn't do it for the wear on the starting gear. Just not worth it.

    It may well be installed on newer cars but I think you will find that's to claim the car manufacturers are trying to be greener. I can't believe there would be a noticable difference if you did this.

    Rumour on google is that it's half a mile worth of fuel per minute. If 30mpg = 16p per mile = 8p per minute of idling

    Do the calcs, it's not hard.

    Usage at idle will be around 0.3 g/hour (Hint: find the average energy content at leave time idle as a variable)
    Next, work out the power usage of the starter motor turning on the engine, make a sensible estimate for additional fuel usage for start up (or ask a Vauxhall owner what their display states as they provide g/hour at low speed). Apply a electricity generation efficiency to the starter motor power. Find out the time variable.

    Then decide that starter motors are expensive and not designed for stop start along with the rest of the engine which will cause additional wear and leave it idling regardless.

    Original Poster

    vibeone;8129455

    If you stopped your car at lights, you would use more fuel … If you stopped your car at lights, you would use more fuel restarting.Plus, you'd look a bit of a tit.



    exactly what i was thinking

    fragaliciousbob;8129638

    Starting an Engine Consumes More Energy Than Running it...



    There are many issues with that 'fact' list. Firstly and most obviously is the statement "So, leaving an engine to idle for more than a minute will use far more fuel than switching the engine off for over a minute before restarting it.". More often than not you will wait well under a minute for a lights-cycle. In cases of heavy traffic, you may start and stop several times, waiting under a minute each time. The 'far more fuel' is contentious; if you wait over a minute you probably will use more fuel, but if you stop the engine at every set of lights thus needing to restart its far from clear cut.

    pghstochaj;8130177

    Do the calcs, it's not hard.Usage at idle will be around 0.3 g/hour … Do the calcs, it's not hard.Usage at idle will be around 0.3 g/hour (Hint: find the average energy content at leave time idle as a variable)Next, work out the power usage of the starter motor turning on the engine, make a sensible estimate for additional fuel usage for start up (or ask a Vauxhall owner what their display states as they provide g/hour at low speed). Apply a electricity generation efficiency to the starter motor power. Find out the time variable.Then decide that starter motors are expensive and not designed for stop start along with the rest of the engine which will cause additional wear and leave it idling regardless.



    I agree with your bottom line, but the point is the calculations are very hard, virtually impossible in fact. Ignore what a meter says the fuel usage is - the meters that report this will be very inaccurate over the starting period; even in a laboratory environment it is not an easy thing to measure. I would suspect that for a typical car the startup energy equates to somewhere between 15-30 seconds worth of idling fuel, but the wear-and-tear is the key factor. I would imagine most cars spend there lifetime without needing a alternator change and possibly a single battery change; cyclical stopping-and-starting will certainly increase the wear on these parts but to quantify it as a cost would be very hard...

    The calculations are definitely not impossible, they will simply be built on a number of reasonable assumptions without an experiment. It's an energy balance. In a lab, fuel use measurements would be extremely simple, both online and start/end for confirmation. They would be accurate to within 1% at worst. A warm engine will use very little additional fuel after a second or two of firing.

    Fuel read outs for idling are also fairly accurate, they have a long averaging period and are simple calculations based on injector flow and injection cycles.

    I would suggest that the main problem is a worn cambelt, they are not designed for start stop and will very quickly wear.

    jah128;8132296

    There are many issues with that 'fact' list. Firstly and most obviously … There are many issues with that 'fact' list. Firstly and most obviously is the statement "So, leaving an engine to idle for more than a minute will use far more fuel than switching the engine off for over a minute before restarting it.". More often than not you will wait well under a minute for a lights-cycle. In cases of heavy traffic, you may start and stop several times, waiting under a minute each time. The 'far more fuel' is contentious; if you wait over a minute you probably will use more fuel, but if you stop the engine at every set of lights thus needing to restart its far from clear cut. I agree with your bottom line, but the point is the calculations are very hard, virtually impossible in fact. Ignore what a meter says the fuel usage is - the meters that report this will be very inaccurate over the starting period; even in a laboratory environment it is not an easy thing to measure. I would suspect that for a typical car the startup energy equates to somewhere between 15-30 seconds worth of idling fuel, but the wear-and-tear is the key factor. I would imagine most cars spend there lifetime without needing a alternator change and possibly a single battery change; cyclical stopping-and-starting will certainly increase the wear on these parts but to quantify it as a cost would be very hard...

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