MPG dropped cold weather anyone else?

Discussion in 'Engine' started by lynall, Dec 5, 2008.

  1. lynall

    lynall Hardcore MB Enthusiast

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    My day to day mpg to work and back is 22mpg 4 miles town 4 miles motorway and 4 more miles in town.

    Last week or so just getting 20mpg used to start at 14/15 mpg building up to 22mpg, but now starting at 13/14 mpg and taking longer to build up and just makes it to 20mpg.

    This morning was 19.3mpg:eek: .

    This is keeping to most speed limits and driving sensibly, giving it some stick and it would drop to 17/18 but this was in the warmer weather.

    Is anyone else getting this or do you think my maf is dying?

    Went to chesham (90 miles) to see wheels in motion the other week and it did its usual 27/28mpg.

    Ps new oil 5 k ago new plugs and leads recently runs and idels smooth and goes like sticky stuff off a stick if you press the pedal hard enough.

    PPs i hate the cold!



    Lynall
     
    Last edited: Dec 5, 2008
  2. NewMB

    NewMB Hardcore MB Enthusiast

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    This is normal in cold weather.

    All cars does it AFAIK.
     
  3. seymansey

    seymansey Hardcore MB Enthusiast

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    Colder air, more dense, better burn = less mpg.
     
    Last edited: Dec 5, 2008
  4. Kompressor_Dude

    Kompressor_Dude Hardcore MB Enthusiast

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    Faster though, on the plus side :D
     
  5. Smatt

    Smatt Hardcore MB Enthusiast

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    Don't forget extra use of electrics sapping mpg: lights, heating, ?heated seats...
     
  6. kjay

    kjay Hardcore MB Enthusiast

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    True!:bannana:

    Ironic though - more power, when you can't use it.

    .
     
  7. BTB 500

    BTB 500 MB Club Veteran

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    This gets raised every winter!

    Lots of factors like extra use of electrics etc.

    Also subtle things like lower tyre pressure in cold weather = higher rolling resistance.
     
  8. Rory

    Rory MB Club Veteran

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    Was surprised how much wifey's Jazz (which I use around town) has dropped off - normally does an easy 50MPG but after the last fill up and reset I can't get it over 45.
     
  9. BTB 500

    BTB 500 MB Club Veteran

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    The extra load from increased use of headlights / fan / HRW / seat heaters / etc. is practically the same for all cars, but on a small & economical car that extra amount of fuel is a much bigger percentage of the normal consumption. Hence the mpg figure is hit harder.
     
  10. OP
    OP
    lynall

    lynall Hardcore MB Enthusiast

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    Bugger and there was me thinking a few quid and mpg back up oh well.

    Regarding elecs i always have headlamps on, climate fan always on, so only additional load is hrw which is so slow its hardly worth switching on:(

    Heated drivers seat doesnt work , but new pads on order:)

    As for more power cant say i have noticed:p



    Lynall
     
  11. kwakdonut

    kwakdonut Hardcore MB Enthusiast

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    + cold start on for longer too!
     
  12. BTB 500

    BTB 500 MB Club Veteran

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    Yup, longer for engine to warm up so increased fuel there.

    Also more battery power used to start the engine (thick oil), which has to be put back ... more fuel used.
     
  13. st13phil

    st13phil MB Club Veteran

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    My W204 is noticeably heavier on fuel when it's raining. I put this down to the brake priming & drying function, but I could be wrong.
     
  14. OP
    OP
    lynall

    lynall Hardcore MB Enthusiast

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    Started at 12.7mpg first thing this morning 5 deg c so no that cold, at journeys end up to 20mpg.
    Be even worse now heated seats fixed:bannana: , strange thing also now boot leak fixed air con has been off and was doing more mpg with a/c on:(



    Lynall
     
  15. Smiley

    Smiley Hardcore MB Enthusiast

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    Err, so you run a 4.3 litre V8 and you are watching the mpg like a hawk. Why not swap it for a E220CDi and just fill it up when it needs fuel?
     
  16. OP
    OP
    lynall

    lynall Hardcore MB Enthusiast

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    Thats 4266cc actually, the extra 34 cc would make it to thirsty:D

    I have always kept an eye on my mpg perhaps i should adopt wifes acttitude to mpg as in dont know/care.



    Lynall
     
  17. OP
    OP
    lynall

    lynall Hardcore MB Enthusiast

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    Just been into town in wifes c320 and computer says 11.3mpg ho ho, mind you its minus 2 deg and i am freezing:crazy:



    Lynall
     
  18. Dieselman

    Dieselman Banned

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    A cold petrol engine uses four times as much fuel as a warm one for the first two or three KM, this then reduces until normal operation is restored after about 12km.

    Your reduction is due to greater thermal losses keeping the engine colder for longer.
    You didn't notice this previously as you drove diesel engined cars, which only use 1.1 times the amount of fuel when cold as opposed to warm.
     
    Last edited: Dec 7, 2008
  19. neilrr

    neilrr MB Club Veteran

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    To the annoyance of my kids I always turn the heat to 'off' on really cold mornings for the first couple of miles figuring the car will warm up much faster that way.

    After about 2 miles I turn the heat on & we're toasty. I didn't realise this would also save petrol.
     
  20. OP
    OP
    lynall

    lynall Hardcore MB Enthusiast

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    DM 4 times as much:eek: when i get bored later i will work that out into a cost per mile.



    Lynall
     

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