Does fuel economy improve in winter ?

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Tue 17 Nov 2009 23:50
Does fuel economy improve in winter ? - diddy1234
Just wondering if fuel economy improves in colder weather or gets worse in winter if the same journeys are made.

For me I noticed with petrol engine cars the fuel economy goes down in colder weather.

Does this also apply with diesel engine cars or does this improve (air density etc) ?

Edited by Pugugly on 18/11/2009 at 10:10

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Wed 18 Nov 2009 00:22
does fuel economy improve in winter - rtj70
does fuel economy improve in winter


No. It degrades for many reasons.
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Wed 18 Nov 2009 00:52
does fuel economy improve in winter - BackOfTheNet
does fuel economy improve in winter


No. It degrades for many reasons.



Such as?

(Oh... not meant to sound snotty rtj70! Just couldn't think how else to phrase it!!)
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Wed 18 Nov 2009 01:06
does fuel economy improve in winter - Rattle
For a start you use a lot more engine power as you need things like head lights, wipers, heater, rear screen heater etc etc. Where do you think the energy to make those things work comes from?
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Wed 18 Nov 2009 01:10
does fuel economy improve in winter - rtj70
For instance:

Cars take longer to warm up.
Diesel has additives (not effecting OP) to stop it waxing.
Petrol does not atomise as well so more unburnt fuel is emitted
Colder air is more dense - this can improve performance but more fuel will be used
Friction - tyres, engine, oils.
Tyres - pressures affected

It's a long list... and I am no expert. We have some on here though. :-)

Edited by rtj70 on 18/11/2009 at 01:11

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Wed 18 Nov 2009 08:43
does fuel economy improve in winter - perro
>>> I am no expert. We have some on here though <<<

I am an ex pert in some things, well - everything actually, and the reason the infernal combustion engine uses more fossil fuel in the winter months is because our planet is further from the Sun at this time of year, although most H J'ers appear to 'take' the Telegraph.
Also, a tail wind can have an effect on MPG - especially with vegetarians!
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Wed 18 Nov 2009 09:08
does fuel economy improve in winter - Old Navy
I assume petrol engines have an electronic version of a "choke" so that they can start and run cold. That would increase consumption in winter, at least you can't hang a handbag on an electronic choke.
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Wed 18 Nov 2009 09:37
does fuel economy improve in winter - Reentrant
the infernal combustion engine uses more fossil fuel in the winter months is because our
planet is further from the Sun at this time of year


No, it's closer now. Perihelion (147 million Km) in January, aphelion (153 million Km) in July.

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Wed 18 Nov 2009 10:04
does fuel economy improve in winter - perro
>>> No, it's closer now. Perihelion (147 million Km) in January, aphelion (153 million Km) in July.
<<<

Is it friend, I didn't know that - so the wev is down to the tilt of the Earths axis then?
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Wed 18 Nov 2009 13:39
does fuel economy improve in winter - zookeeper
>> the infernal combustion engine uses more fossil fuel in the winter months is because
our
>> planet is further from the Sun at this time of year
No it's closer now. Perihelion (147 million Km) in January aphelion (153 million Km) in
July.



but its winter in australia in july, swings and roundabouts
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Wed 18 Nov 2009 09:43
does fuel economy improve in winter - L'escargot
Mine (all of which have been petrol) have all given worse economy in winter. I always plot graphs of the monthly average mpg against the month of the year, and this shows it conclusively.

Edited by L'escargot on 18/11/2009 at 09:46

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Wed 18 Nov 2009 10:14
does fuel economy improve in winter - Red Baron
No!

I have both a petrol and a diesel car. The petrol does longer journeys and its MPG drops by about 5 percent. The diesel does short journeys and its MPG drops by up to 25 percent!

The heater uses energy, so the engine must work harder to maintain the same speed. Wet roads, especially those with poor drainage require considerably more effort to drive through. Windier conditions equally require more throttle input to maintain speed.

The variations in the density of air are almost insignificant in this perspective.
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Wed 18 Nov 2009 11:08
does fuel economy improve in winter - Andrew-T
Windier conditions equally require more throttle input to maintain speed


Ignoring the whimsical reference to vegetarians above, shouldn't the effect of head and tail winds cancel out? Just as one recovers some of the energy used climbing a hill when going down the other side? But I suppose sidewinds must have some negative effect ...
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Wed 18 Nov 2009 11:20
does fuel economy improve in winter - dieseldogg
Well Red Baron Consider that the lesser theromdynamic efficency of the petrol engine means it dumps more heat for the same power out put
therefore the heater works faster in a petrol
So therefore to get usuable heat out of a modern diesel in the winter for demisting etc
it takes longer to warm up
therefore its relitive efficiency will be lower in the winter
Or sommat along those lines
diesels (some of) now got eberspracher aux heaters
for this reason
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Wed 18 Nov 2009 12:23
does fuel economy improve in winter - Reentrant
The heater uses energy so the engine must work harder to maintain the same speed.


The engine doesn't care if the cooling system is dumping waste heat to the radiator or the heater matrix.

(Unless you meant a windscreen heater. I don't know how much extra resistance that would put on the alternator pulley)
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Wed 18 Nov 2009 12:31
does fuel economy improve in winter - dieseldogg
Sniff
That is neither what I said or indeed even meant
Hint
I used the word "dumps" heat
However the diesel being more efficient has less heat to dump
and forby
I wondered if the driver let the vehicle warm up before driving off.
me
i do as my manual instructed & move immediately after starting the vehicle
Back to my halo polishing
& penny counting
cheers
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