Fuel Economy Tips
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  1. #1
    2000+ Brad's Avatar
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    Fuel Economy Tips

    This was brought up in the Performance Thread and I think it might serve as a good topic for discussion in here.

    What are people's tips and experiences on trying to improve fuel economy?

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    What has been found to be true and tried and what is total BS?
    B to the R to the A from the D
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  2. #2
    Fellow Frogger!
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    get yourself a 1.3 litre

    sorry, couldn't resist

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    Single biggest difference for me was the Beru multi-electrode spark plugs recommended by Auto France. I always check my fuel consumption and write it in L/100km on the bottom of the docket, so it was a consistent 10% improvement with those spark plugs than with the old single electrode ones.

    Driving style doesn't seem to affect it too much. In the city, it's always 9-10L/100km (depends mainly on whether you've got the aircon on) and country is 6.5-7.5L/100km, depending on how fast you drive. It seems *most* efficient at 100 on the highway (100km/hr = 3000rpm = peak torque maybe that has something to do with it?) and if you drive a bit faster, say around 110-115 you use 7.5L/100km travelled... that means, travelling at 110 on the motorway to Melbourne I'll use 9L extra fuel over travelling at 100km/hr, but I'll save 50 minutes travelling time... I guess if economy was everything I'd slow down 10km/h hey?

    Derek

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    Gone Fishin' Ray Bell's Avatar
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    10% is a huge improvement... I got near that with the Cadillac oil, but you've convinced me I should try those plugs.

  5. #5
    rek
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    Ray,

    What weight is the Cadillac Oil?
    Peter
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  6. #6
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    Ray,

    We changed to the Beru plugs in our XM (when we had it) and my 306 and noticed the difference. I am sure that was the difference as I didn't change anything else and I keep my fuel dockets in the glove box till it overflows so I can compare

    I assume you get extra power too if you're prepared to blow fuel economy out the window?!

    Derek.

  7. #7
    1000+ Posts alan moore's Avatar
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    I changed to Bosch Super 4 ,similar to the Beru at a similar price of $9 ea and have found a consistant 8% better economy over the last 10000Km in my 306. They easily pay for themselves.
    I assume they work better in 16 valve heads with central plug location, but there may be an improvement on all types.
    Alan.
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  8. #8
    Sense Pug307's Avatar
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    If you think of it logically, the amount of fuel you burn is directly proportional to the amount of work you are doing. Engine and drivetrain loses asside and provided you do not labor the engine (like floor it up a hill in 5th/1200rpm), the same amount of work is being done to drive up a hill in 2nd/4000rpm or in 3rd/3000rpm for example. Therefore, provided you are not accelerating hard and braking hard at every set of lights, the style of driving, whether you change at 3k or 6k should not use anymore fuel.

    IMHO, I would think that keeping the revs up and staying in a lower gear rather than being in a higher gear and labouring with WOT is much more fuel efficient and is better for the engine.
    N.B: below picture is only an extreme example of what is possible given optimal conditions, not necessarily representative of day to day driving.

    <img src="http://users.bigpond.net.au/skystar/pictures/307xs-tripcompfc.jpg" alt=" - " />

    As someone that drives with a trip computer - I can tell the difference between maintaining the same speed in different gears.

    The higher the gear, the lower the fuel consumption for a given speed (provided the car can maintain the speed in this gear).

    This is taught to students in Germany - I was cynical at first, thinking, how on earth can I use less fuel nearly flooring it in 4th, than climbing in 3rd or 2nd with a smaller throttle input. Granted I didn't try this at 1200rpm - but there are reasons why you wouldn't want to. The trip computer didn't lie and supported my friend's case.

    For this reason, I'm happy to upshift to 5th gear in a manual to cruise at 60km/h or even slightly less. Why do you need a lower gear if you're cruising on a fairly level road? You don't need the performance when you're cruising. If you need to overtake - downshift, that is logical. But if you want to save fuel, there's no harm in using the highest gear (provided we're not revving at 1200rpm) - there is no problem provided you are not lugging the engine. Cruising on a level road, I doubt you will.

    I'm not sure as to whether this theory applies to carburettor cars. Think about it - when you are in a higher gear, there are fewer revs per minute & hence fewer cycles of fuel going into the engine. It appears, although in a higher gear you *may* (not always) press the throttle harder, injecting more fuel per cycle (you can only inject so much fuel), you have FEWER cycles to begin with - overall the fuel consumption is reduced. I'd imagine higher revs would create greater frictional losses.

    Personally - I believe, maintaining the highest gear possible is one of the best way to save fuel - coupled with sensible driving.

    BTW: If you ever though you'd use less fuel going down a hill in neutral, you're wrong You actually use less fuel whilst in gear coasting down a hill - ask if you can't see why. Initially you might not see it, but it's quite logical once it's explained.

    Peugeot 307 XS 1.6
    Aussiefrogged in MEL, PER, SYD, BNE & ADL.
    Rendezvous Adelaide 2005

  9. #9
    Gone Fishin' Ray Bell's Avatar
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    rek:
    Ray,

    What weight is the Cadillac Oil?
    They are a specialist supplier, so they have to have everything... and they supply what the manufacturer lists for your car.

    20W 50 I think I'm using.

  10. #10
    2000+ Brad's Avatar
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    Re using less fuel while coasting rather than going into neutral, I would think this to be because on most modern fuel injection cars, the fuel is shutoff when coasting in gear as opposed to fuel being injected when idleing in neutral.

    PS. Plz explain why you are using the 'loud' function of your radio?

    <small>[ 02 March 2003, 10:34 PM: Message edited by: Phasis ]</small>
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    That'd be the only time coasting in neutral would use more fuel - in cars with fuel cutoff on overrun. Which doesn't even cover all injected cars currently on sale.

    Stuey


    2003 PEUGEOT 206 GTi

  12. #12
    Sense Pug307's Avatar
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    Simple physics I guess.

    In neutral, the engine must power itself.

    In gear, the engine does not need to power itself, as the gravity causing the car to descend, ensures the wheels are spinning, which spins the engine via the powertrain. You need a direct link - for this to work properly, ie. a manual or a locked up torque converter.

    The 307's auto locks up normally, unless you go below 1200 or so rpm. You can actually watch the fuel consumption increase from 0 going down hill in 4th as the torque converter unlocks - the fluid coupling doesn't transfer the energy very well.

    Once it's explained it's quite obvious. Just initially, when you ask that question - everyone says neutral uses less fuel.

    LOUD

    Funny thing is, when you put the stereo on LOUD, you can't turn the volume up as much. At lowish volume levels you can sense some distortion with LOUD on - you don't need high volumes in the 307 - it's fairly well hushed. But the audio's nothing great - probably one of the few cars whose treble is about the only thing worth talking about, audiowise.

    Peugeot 307 XS 1.6
    Aussiefrogged in MEL, PER, SYD, BNE & ADL.
    Rendezvous Adelaide 2005

  13. #13
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    The LOUDNESS control on sound equipment is simply a piece of circuitry which accentuates the Bass and Treble so that the reproduction sounds normal at low volume levels where your hearing is less efficient at picking up the extreme high and extreme low frequencies.
    Sometimes this is done automatically as the volume control is turned down, since this was no longer a normal volume control it was referred to as a Loudness Control.

    GRaham Wallis

  14. #14
    Sense Pug307's Avatar
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    I know that - and Phasis is pretty cluey with his audio, so I assumed he knew that too

    I'm not sure whether it's the headunit or the speakers which contribute to the average sound. Funnily enough, some people have told me that the audio is better with LOUD off. In any case, the distortion is certainly reduced.

    Peugeot 307 XS 1.6
    Aussiefrogged in MEL, PER, SYD, BNE & ADL.
    Rendezvous Adelaide 2005

  15. #15
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    Justin,
    The boosted Bass is probably overloading the speaker or amplifier at a relatively low sound level.
    I agree,the 307 sound system is probabaly no better than the very ordinary one fitted to the 505s.
    On the other hand the one fitted to the 406 is excellent.
    Fascinating to find though, that the AM tuner starts at around 200khz and goes to 1600Khz in one band.
    You get to listen to aircraft navigation beacons if you do a search tune from the bottom end!

    Graham

  16. #16
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    Pug307:
    Simple physics I guess.

    In neutral, the engine must power itself.

    In gear, the engine does not need to power itself, as the gravity causing the car to descend, ensures the wheels are spinning, which spins the engine via the powertrain. You need a direct link - for this to work properly, ie. a manual or a locked up torque converter.

    The 307's auto locks up normally, unless you go below 1200 or so rpm. You can actually watch the fuel consumption increase from 0 going down hill in 4th as the torque converter unlocks - the fluid coupling doesn't transfer the energy very well.

    Once it's explained it's quite obvious. Just initially, when you ask that question - everyone says neutral uses less fuel.
    Justin, it still depends on the car...most carburettored cars would use more in gear as the vacuum would be greater on the carb in gear. And without empirical evidence, my gut would say that the older injected cars (say, with Bosch CIS) would also use more at 3000rpm in gear than 900 out of gear. But, interesting anyway.

    Once heard that those economy drive experts accellerate quite rapidly through the gears then get into the highest gear, which surprised me.

    Cheers

    Stuey


    2003 PEUGEOT 206 GTi

  17. #17
    1000+ Posts silverexec's Avatar
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    Once it's explained it's quite obvious. Just initially, when you ask that question - everyone says neutral uses less fuel.
    And just recently I started moving into Neutral to save fuel going downhill. mallet

    There goes that great idea... roll_lau

    Richard
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  18. #18
    Real cars have hydraulics DoubleChevron's Avatar
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    Hi Guys,

    since way back in the 'D'jectronic days (ie: even my old 72 DS21) fuel injection actualy SWITCHES OFF the injectors on the overrun. ie: If the throttle is closed, and the motor is doing more than 1800rpm the injectors are shut off to save fuel (as your obviously on the over run). As soon as the revs hit 1200rpm the injectors are turned back on to prevent stalling.

    When I 1st got my DS21 running, this caused some very strange behaviour. As every setting in the last 15years had been tampered with in an attempt to get the car running, it was idling at about 2000rpm. This meant as soon as I wasn't revving the car, it would sit there, rev itself to 1800rpm at which stage the injectors would turn off (as the accelerator was closed), then as soon as the revs dropped to 1200rpm the injectors would cut back in to prevent stalling.

    So if the car was just left idling it'd cycle constantly from 1200 to 1800rpm. wierd .....

    seeya,
    Shane L.
    PS: Now you know why throwing an injected car into nuetral actualy *uses* more fuel.
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  19. #19
    Fellow Frogger!
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    Just like the D's shane metioned, the 505 GTi has a fuel cut off relay on overun (when the butterfly is completley closed), and i to had much trouble with it failing to cut in again. The car still stalls every morning coming out of my driveway because of this stupid feature

    Ahhwell.
    Jason Judd
    <img border="0" alt="[Peugeot Emblem]" title="" src="graemlins/peugeot.gif" /> '85 505 GTi Executive
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  20. #20
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    That's wrong, Shane. Sorry to sound argumentative. Not all injected cars have a fuel shut off on the overrun. Not even some of the later (than D-Jet) L-Jet systems, and none of the K-Jets before the KE-Jetronic, had fuel cut off.

    (edit...I don't mean you're wrong about the D-Jet!)

    Stuey

    <small>[ 03 March 2003, 06:17 PM: Message edited by: Stuey ]</small>


    2003 PEUGEOT 206 GTi

  21. #21
    Sense Pug307's Avatar
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    Ahh, I should've put a little disclaimer about fuel injection, I thought I mentioned it.

    Another good tip - if you want to save fuel, reduce your cruising speed at higher speeds. I've noticed that cruising at 110km/h uses noticeably more fuel than 100km/h. At higher speeds, drag starts to become important. I would suspect the car is near best efficiency at around 80 km/h. Driving slower when you're at 50 won't do you much good.

    Have to say that trip computers are great - other than the road, they give you something to look at when driving.

    Granted you have to weigh up the time/cost benefit. One thing's for sure, you won't get a speeding fine cruising 'less fast'

    Graham, the radio in the 307 goes from 144 to 288, then onto 500 something till the end of the 1600s. I think I caught some form of NDB in the high 200s - I could hear the morse code. Haven't found any with live ATIS or anything like that

    Do we have many NDBs in the sub 288 range in Melbourne? I can only think of Plenty, otherwise everything else is in the 300s.

    Peugeot 307 XS 1.6
    Aussiefrogged in MEL, PER, SYD, BNE & ADL.
    Rendezvous Adelaide 2005

  22. #22
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    Justin,
    Until recently I worked for Airservices Australia and could have got you a list.
    NDBs are pretty much obsolete nowadays.
    I managed to receive the ATI at Townsville airport when I was there.

    Graham

  23. #23
    1000+ Posts silverexec's Avatar
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    I've got an old list here of NDBs given to me by a friend who's in to all this stuff, I don't know how current it is though.

    Here are the ones in the 144 to 288 range:

    212 BNS Bairnsdale
    239 BLT Ballarat
    245 BDG Bendigo
    275 CWS Cowes
    203 HML Hamilton
    254 MNG Mangalore
    284 MFD Mansfield
    218 PLE Plenty
    206 ARC Arcadia
    230 MEA Meadow
    227 LVG Mount Livingstone
    233 MWM Mount William
    212 POD Portland
    212 SHT Shepparton
    203 WGT Wangaratta
    209 WKB Warracknabeal

    Some of these seem to have the same frequency, so I guess you'd be unlikely to pick them up if you were too far away from them. A long time ago I identified quite a few of these on an old LW radio I've got.

    Enjoy.

    Richard
    - Richard

    Now: 405 SRI D70 '93
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  24. #24
    Sense Pug307's Avatar
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    Thanks for that Richard - NDBs are basically like AM radio stations (actually IIRC, one of the stations in SYD also functions as an NDB).

    Have to say "218 - Plenty AM" was pretty boring tonight

    Peugeot 307 XS 1.6
    Aussiefrogged in MEL, PER, SYD, BNE & ADL.
    Rendezvous Adelaide 2005

  25. #25
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    It's interesting to note that I noticed no change in fuel economy between using 5th gear and 4th gear in 504s/505s. I have noticed an economy improvement after fitting a genuine 505 big bore exhaust manifold which is tuned 4-2-1 system.

    On another note I had to use the AU Falcon last night at work. It uses HEAPS of fuel, even without a load and when driven gently. My 505 fitted with a trailer load of stuff (so it weighed as much as the Falcon) got better economy. I don't know how Ford can possibly build such a thirsty EFI car.

    The AU Falcon reminded me of my old TE Cortina, although the Cortina felt a bit better. The scariest thing about the Falcon was the broken headlight switch, which almost caused an accident on the freeway.

    Dave
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