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  • harryhound
    Hi,
    I have a very large silver trophy in my house which was won by my great uncle in 1953, in a competition organised by Shell Oil to see who could drive furthest across the desert on one tank of fuel.
    He won in a very large Jaguar, and his technique was to drive as fast as possible, then turn the engine off and coast, then drive as fast as possible, then coast etc etc. Would be interesting to see how that compares with doing 56mph constantly eh?! Sadly this doesn't work in my current modern car because as soon as I switch the engine off the steering and brakes go - oops!
    Originally posted by craptiger
    A couple of years ago I used to drive an diesel Vectra Estate (company car). In the handbook it said something like "Do not freewheel down hills, this will give you worse MPG, as the engine management system shuts off the fuel input to the engine automatically" and as you say, when the engine stops going round the brakes and steering suffer.

    I used to regularly drive up and down the M4 (I worked in Swindon) and found the best way to get increased economy is to drive about 3 or 4 car lengths behind an artic in the low pressure zone behind them.

    I would like to thank the driver on the A2/M2 who allowed me to do this trick on sidelights for over 60 miles, when the alternator on my mother's aged Fiesta wore out its brushes in the early hours. It probably unsettled him almost as much as us, 'cos we were worried about running out of both petrol and electricity, but we made it home
    Last edited by harryhound; 16-01-2008 at 10:24 AM.
    • feyaz
    • By feyaz 16th Jan 08, 10:21 AM
    • 21 Posts
    • 6 Thanks
    feyaz
    lets all do this
    Lets all do this, decrease traffic flow and increase congestion even more, if you want to get to places slowly then walk or take the bus. if you want to concerntrate more on the trip computer than the road be my guest but if you crash into the back of my car expect a broken nose on you car and your face!!!!!!
    • davetrousers
    • By davetrousers 16th Jan 08, 10:24 AM
    • 5,639 Posts
    • 4,881 Thanks
    davetrousers
    WTF?

    maybe you should concerntrate (sic) on other things
    .....

  • chimp choker
    When I drive I aim to not have to use the brakes, I find this helps greatly, you are always consious of your speed because you have to think ahead, you tend not to drive too close to the car in front, you are constantly aware of the need to slow down at junctions etc and you save on wear to the braking system as well as becomming more confident and calm. I believe if more people adopted this form of driving there would be less problems on the roads The best way to drive is to be relaxed and calm and NOT to go racing around, every time you accelerate heavy you are pouring fuel into the engine, if you suddenly need to stop you strip material off your brakes....
    I drive a Ford Scorpio 2.3 and used to spend 50 a week on petrol. I had it converted to LPG and now spend about 25 a fortnight for the same mileage, I don't even bother to monitor the mileage now.
    When I first had it converted I went fro HULL to BRISTOL for 18.50... can't be bad...
    Originally posted by caretakerPete
    I drive a miggy 2.6 v6 auto so I generally get around 17 mpg in town and 26 on a run. I drive defensively as opposed to offensively and the difference is better fuel economy, safer driving and more calmness when I get there. I am going to see James Blunt in nottingham on Saturday so I'll test the millage on this trip.
  • stoutgoose
    Fuel Injection.
    The fuel injection system design of modern cars; both petrol and diesel is such that when the driver lifts their foot from the gas pedal whilst in gear, allowing the car to decelerate; e.g. approaching a junction, no fuel is injected into the engine. Instead the vehicles' momentum; whereby the wheels rotating over the road surface, keep the engine turning over via the vehicles' drive-train (differential and gearbox).

    You can take two points from this;

    1. People who put the car into neutral and coast up to junctions and down hills are actually usuing more fuel than if they lifted their foot from the gas pedal.

    2. As has been mentioned by many people in this thread; judging the road feature ahead and anticipating the slowing distance required allows the driver to lift off the gas earlier, therefore allowing maximum momentum driven decelleration, resulting in increased fuel economy.
    • almillar
    • By almillar 16th Jan 08, 10:50 AM
    • 8,164 Posts
    • 3,369 Thanks
    almillar
    One thing that hasn't really been mentioned too much here is staying back from the vehicle in front. I am a fast driver, I overtake often and am usually driving at the speed limit, but I also usually slow down for things before the 'slower' driver in front of me has. Cruising up to roundabouts is something I don't like - you may be able to go without having to stop, so approach it almost as if you want to go, rather than want to stop. Conversly, if the lights are red, you should cruise up to them, increasing the chance that they'll turn green before you get to them, meaning you won't have to stop. I hope that makes sense?!!
    Just remember that cruising at a constant speed on the flat, even up to 70, is pretty economical, acceleration is the real killer, but more that that, accelerating from a standstill is hardest - anyone who has had to push a car will understand this!
    Please don't crawl all over the country either - before you do your economy experiments, have a look in your mirror to see if you're holding anyone up!
    Alan
  • Bartlam
    Love the idea of using no petrol!
    Love the idea of the engine using no petrol! However running the car on fumes to test fuel consumption (I was told by a mechanic) is not a good idea with modern fuel injected engines as the gunk in the the bottom of the petrol tank gets forced through the injectors which can clog them and result in an expensive trip to the garage (even if you freewheel all the way).

    Go with the flow
    I try to use engine momentum in traffic at lights etc. whenever possible but often find I seem to have picked up another car behind me who's driving like he's attached to my boot - i.e. a tad impatient.
    I think many problems and a great deal of stress could be avoided by actually driving as though there are other people on the road. I'm told that ex bikers (yup, hands up) often make good car drivers as you never seem to forget that your survival depends on very good anticipation and use of peripheral vision.
    Shop windows can be used as big mirrors when in town enabling you to see far further up the road or round corners (and park in very tight spaces).

    Here's a little challenge for everyone though. Why not use the engine breaking method to ease the flow of traffic by letting a car out of that junction that everyone in front can't seem to see? I've found that you don't need to jam on the anchors, just look ahead, let the car slow a bit, flash your lights & let the poor guy out. I usually find that the car you let in will then let someone in at the next junction and so on. We don't get there any later, save fuel and we all feel good about ourselves into the bargain...


  • racheldawson
    I also have an MPG display option in my Citrone, which can be entertaining on long journeys to see what's the biggest number you can make it display.

    No one seems to have mentioned the email going about suggesting a boycott of BP and Shell, for those who are interested here it is;

    Philip Hollsworth offered this good idea:

    This makes MUCH MORE SENSE than the 'don't buy petrol on a certain day campaign that was going around last April or May! The oil companies just laughed at that because they knew we wouldn't continue to hurt ourselves by refusing to buy petrol. It was more of an inconvenience to us than it was a problem for them. BUT,whoever thought of this idea, has come up with a plan that can really work.

    Please read it and join in!

    Now that the oil companies and the OPEC nations have conditioned us to think that the cost of a litre is CHEAP, we need to take aggressive action to teach them that BUYERS control the market place not sellers. With the price of petrol going up more each day, we consumers need to take action. The only way we are going to see the price of petrol come down is if we hit someone in the pocket by not purchasing their Petrol! And we can do that WITHOUT hurting ourselves. Here's the idea:

    For the rest of this year DON'T purchase ANY petrol from the two biggest oil companies (which now are one), ESSO and BP.

    If they are not selling any petrol, they will be inclined to reduce their prices. If they reduce their prices, the other companies will have to follow suit. But to have an impact we need to reach literally millions of Esso and BP petrol buyers. It's really simple to do!!

    Now, don't wimp out on me at this point... keep reading and I'll explain how simple it is to reach millions of people!!

    I am sending this note to a lot of people. If each of you send it to at least ten more (30 x 10 = 300)... and those 300 send it to at least ten more (300 x 10 = 3,000) ... and so on, by the time the message reaches the sixth generation of people, we will have reached over THREE MILLION consumers! If those three million get excited and
    pass this on to ten friends each, then 30 million people will have been contacted! If it goes one level further, you guessed it... ..

    THREE HUNDRED MILLIONPEOPLE!!!

    Again, all You have to do is send this to 10 people. That's all.(and not buy at ESSO/BP) How long would all that take? If each of us sends this email out to ten more people within one day of receipt, all 300 MILLION people could conceivably be contacted within the next 8days!!! Acting together we can make a difference If this makes sense to you, please pass this message on.

    PLEASE HOLD OUT UNTIL THEY LOWER THEIR PRICES TO THE 69p a LITRE RANGE

    It's easy to make this happen. Just forward this email, and buy your petrol at Shell, Asda,Tesco, Sainsburys, Morrisons Jet etc. i.e. boycott BP and Esso
    Last edited by racheldawson; 16-01-2008 at 11:43 AM. Reason: too many spaces
    • anewman
    • By anewman 16th Jan 08, 11:46 AM
    • 8,786 Posts
    • 6,259 Thanks
    anewman
    Hi

    Me & Mr SMF are trying really hard not to use our car at all. We have a Scenic. The problem with this is that often the battery goes flat through lack of use and we are continually having to recharge it. We have bought a solar pannel which tries to get it "juiced up" but does anyone have any other ideas or share our problem We can't live without a car completely.:rolleyes:
    Originally posted by setmefree2
    Get a spanner and undo the negative terminal after you have used the car and re-connect when you want to use it. If you barely use the car, it won't be too much trouble - and it will also give you an opportunity to check coolant and oil etc.
    • MSE Martin
    • By MSE Martin 16th Jan 08, 12:11 PM
    • 8,116 Posts
    • 42,310 Thanks
    MSE Martin
    Just a quick note on avoiding BP and shell. This has been sent to me many times - the problem is the margins are so small its irrelevant - the vast majority of what we pay doesn't go to BP and Shell it goes to tax. If you see the cheapest petrol article you can see the stats.
    Martin Lewis, Money Saving Expert.
    Please note, answers don't constitute financial advice, it is based on generalised journalistic research. Always ensure any decision is made with regards to your own individual circumstance.

    Don't miss out on urgent MoneySaving, get my weekly e-mail at www.moneysavingexpert.com/tips.

    Debt-Free Wannabee Official Nerd Club: (Honorary) Members number 000
    • anewman
    • By anewman 16th Jan 08, 12:24 PM
    • 8,786 Posts
    • 6,259 Thanks
    anewman
    Plus such an email/campaign is never likely to reduce the sales of those companies, otherwise with all the effort made already we'd expect their forecourts to be empty.

    And like Martin says, their £x bn profits aren't from their petrol stations, there are many uses for the oil they get. Just look at this list of petrochemicals http://en.wikipedia.org/wiki/Petrochemical Some of these chemicals are used by us everyday.
  • schoolfundraiser
    56mph is used because it is the highest speed one can travel at without incurring wind resistance. I usually push my driving up to 60mph as wind resistence is still not very significant. The difference in fuel consumption between 60mph and 70mph is very significant, though.
    Originally posted by crossleydd42
    I regularly drive a 140 mile round trip to see my elderly dad and which in my small car would cost about 13 in petrol (pre price rises). I found that by keeping my speed to about 60 mph I saved a couple of quid per trip and the journey only took an extra ten minutes. It is also less stressful as you can tootle along behind the lorries in the slow lane and don't get bugged by the "can't wait to pass you so I will hang on your tail or overtake on the inside on the motorway and then cut in front of you dangerously in your blind spot just as you are about to pull in to the slow lane" drivers.

    On the subject of engine versus brakes wear I was taught to drive smoothly - my driving instructor's keyword was ANTICIPATION. Using your brakes unnecessarily was a mortal sin in his eyes and smooth driving was the aim. Slowing down by releasing the pressure on the accelerator as you approach a junction is a safety measure and as your speed decreases your gearing should match this in the same way that it should match it when accelerating.

    By the way one way to improve the smoothness of your driving is to put a load of empty bottles in a loose box in the boot and you will then get an audible indicator of jerky driving. And an unsecured planted up and recently watered pot of flowering plants will show you what happens when you take corners too sharply too - a real mess in the boot to clear up even if the pot doesn't actually break!
    • tomstickland
    • By tomstickland 16th Jan 08, 1:10 PM
    • 18,904 Posts
    • 15,428 Thanks
    tomstickland
    you cannnot accuratley judge fuel efficiency by volume guys and gals, sorry, petrol increases and decreases in volume according to its temperature, the only way to accurately judge fuel economy would be to weigh the fuel in the tank before and after the test period, trip computers in cars arent too good either, putting a different set of wheels/tyres on your car can make a huge difference to the reading also as your changing the outer circumference of the wheels
    Originally posted by kaya
    The "brim the tank" method is the most reliable way of measuring mpg. If you have a tank size of 11 gallons and the brim point is uncertain to, say, +/-1/4 of gallon the you have an uncertainty of 0.25/11 ie: around 2.5%. If you managed 400 miles on the thankthen the result is 36mpg +/-0.9mpg. That's good enough to see if careful driving is giving you a worthwhile result. The power of averaging over a number of readings will give more confidence in the results.

    Since fuel consumption is a function of engine efficiency and the amount of work done then it's fairly simple to see how to cut consumption.
    On the economy front a petrol engine makes best steady state efficiency at somewhere around 2000-3000rpm.
    Regarding work done, acceleration itself is necessary, and hard acceleration is fine. It's unecessary acceleration followed by heavy braking, or erratic acceleratino/braking instead of maintaining a steady speed that's wasteful. Every braking operation is turning momentum into heat. ie: fuel into waste heat.

    Edit: The expansion coefficient for Gasoline is just under 1000ppm/deg C. The volumetric expansion factor is approximately 3 times this which gives 0.3% per deg C. Say there's a 10% change in temperature between the before and after fuel measurements then there'd be a 3% error. Once again, the error is at a level that's tolerable given the expectations of the experiement. The combined uncertainty from temperature and tank brimming would be around
    sqrt(2)*3 = 4% ish.
    Since a 10% change in fuel consumption would be regarded as meaningful, 4% of uncertainty is fine.
    Last edited by tomstickland; 16-01-2008 at 1:41 PM.
    • davetrousers
    • By davetrousers 16th Jan 08, 1:24 PM
    • 5,639 Posts
    • 4,881 Thanks
    davetrousers
    No one seems to have mentioned the email going about suggesting a boycott of BP and Shell, for those who are interested here it is;
    Originally posted by racheldawson

    People on this forum are fed up with this being posted every other day!

    Please edit your post to delete this bit. Thanks

    Another thing THERE AREN'T 300 MILLION PEOPLE IN BRITAIN
    .....

  • rygon
    I cant remember who said to not use the petrol stations air for inflating your tyres as it is unreliable? What do you use instead. Ive seen those Tyre air compressors made by RAC etc which pump up to 300psi...with me only needing 32psi and the gauge going up in 10's then, to me, that is a lot less reliable. Im sure the stations will have to have their pressure gauges calibrated every so often as well for legal reasons so i cant imagine them being too far out. I agree with the heat of the tyres though but my nearest station is only 2miles away and at a constant speed (ie not using brakes much) my tyres dont get that warm in that little distance
    Smile and be happy, things can usually get worse!
  • harryhound
    The energy and danger in a moving body is proportional to square of the speed
    Lets all do this, decrease traffic flow and increase congestion even more, if you want to get to places slowly then walk or take the bus.
    Originally posted by feyaz
    Guess the speed that gets the most cars down a stretch of road in a given time?

    If a stop and start and slam on the brakes crash test dummy causes a "ripple" the speed falls below this magic number and a traffic jam then develops. Not to mention the number of tailgating drivers who then have near misses or worst "kiss" bumpers, putting a lane out of action for a good 20 minutes.

    Harry.
  • John 3:16
    DRIVE with an egg on the bottom of your shoe.

    OK use a pretend egg.
  • neil.dalton
    Interestingly I did the same the other week driving from Somerset to Sheffield on the same roads, all motorway, and then repeating the journey later on but accelerating more carefully, not using cruise control, and checking the mileage manually and with the car's trip computer. I drive a Honda Accord Tourer with a 2.2 diesel engine and on the journey where I drove "normally" I achieved 43 mpg. However on the more "careful" journey I managed 49 mpg. For a big car, especially an estate, that's quite a creditable increase. Driving an average 12000 miles per year that must be a decent saving. The journey only took me ten minutes longer believe it or not and was more stress free. I do the same all the time now, and notice even bigger savings with my normal urban/rural commute when the speed is lower, in the 40mph to 60mph region. Ever now and again however I do drive more "spiritedly" for short journeys, as I believe it is actually good for the car.
  • kayj_prod
    It also means that the shortest route is seldom the most economical, as it usually involves lots of junctions and minor roads. (Unless you're travelling on a bicycle, of course, where the cruising speed isn't very high, so distance is more important than cruising. )
    Originally posted by charlieheard
    I've been monitoring my fuel for a week through my journey to work. I've now worked out that a longer journey- going out of my way to the nearest main trunk road- saves me considerable fuel compared to the shorter journey on B/C roads. The best indicator is how few times I HAVE to change gear or decelerate. The journey isn't quite as scenic though!

    I used to drive a Discovery and got the boy racer out of me then. Fortunately, I've kept that mentality in mind and my 2.2 Diesel hasn't been over 2000rpm in weeks!
    • webwiz
    • By webwiz 16th Jan 08, 7:18 PM
    • 209 Posts
    • 77 Thanks
    webwiz
    My car gives an instant fuel consumption figure. I dont know how accurate it is but it consistently shows that on a level motorway using the cruise control it does just under 1 mpg less for each 1 mph more between 60 mph and 80 mph. It is a Peugeot 406 diesel.
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