MPG dropped cold weather anyone else?

[lynall]

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 .

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

 

[NewMB]

This is normal in cold weather.

All cars does it AFAIK.

 

[seymansey]

Colder air, more dense, better burn = less mpg.

 

[Kompressor_Dude]

Faster though, on the plus side

 

[Smatt]

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

 

[kjay]

Faster though, on the plus side

True!:bannana:

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

.

 

[BTB 500]

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.

 

[Rory]

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.

 

[BTB 500]

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.

 

[lynall]

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



Lynall

 

[kwakdonut]

Colder air, more dense, better burn = less mpg.

+ cold start on for longer too!

 

[BTB 500]

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.

 

[st13phil]

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.

 

[lynall]

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

 

[Smiley]

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?

 

[lynall]

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

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



Lynall

 

[lynall]

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



Lynall

 

[Dieselman]

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.

 

[neilrr]

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.

 

[lynall]

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



Lynall