Cold Weather Fuel Consumption

[Rabbers]

Has anybody figured out just how badly the 300h's petrol consumption is affected by cold

weather?

This past month my car has been parked in the open with night temperatures having reached

around -10°C before rising to 3-5°C by the time I am ready to drive off in the morning. Some-

times I scrape ice off the windscreen but usually prefer to let the from fan/demister melt most

of it before I turn on the wipers. I also always turn on the rear window/side.mirrors defroster

and sometimes the seat heating, and, since I usually forget to previously switch it off, the

audio comes on - as do the auto headlights. So, by the time I move off, the car has been

idling for at least 3-4 minutes with most of the electricals consuming power, and I know that

this is a bad thing.

And yet, while I believe that my fuel consumption since summer/autumn has increased, this

is more of a strong suspicion than a quantifiable fact. Can it be that my trips with a cold

engine are customarily not short and that I am lucky to be able to drive gently and steadily

for the first 12-13km from home before joining major roads with the engine nicely warmed up,

the viscosity of the petrol and other fluids normalized, and the regenerative braking system

fully effective?

[Steve44]

short journeys i think are affected by 8 to 10mpg, longer ones, 3 to 5 by my pretty unscientific analysis. It takes much longer for the car to warm up enough to allow EV to power the car without the engine.

[ColinBarber]

Yes I think up to 10% on long journeys and maybe even up to 20% for very short ones.

[Beejay55]

There is a small up-side to the cold weather. The petrol you buy is a little denser in cold weather, giving you 'more bang for your buck'.

[dochybrid]

I think slight temperature change has got moderate impact on mpgs..

last week or so I had local mpg 41.5, with some improvement in weather it has gone up to 44.3

Over the weekend, 125 miles motorway, 52.9 mpg when temperature gauge showed 10C

On return with temperature of 6C,mpg on the same journey went down to 49.8 mpg

Difficult to quantify the exact impact though a good news for all us, in particular newbies, who might be gutted seeing very low winter mpgs..

[michaelH]

Broadly similar experience to dochybrid - mpg had dropped to mid 40s with combination of cold weather and new winter tyres, but has picked up recently. Just got back from a trip up to Yorkshire with two passengers, driving around Yorkshire with four passengers and back to Leicester again with the two I started with. MPG now reads 53.1 and on past evidence that will mean about 50.5 mpg at the pumps. Not much chance to speed on the M1 (cameras and road works for much of the journey) but Yorkshire was hilly and we were heavily laden. Filled with Shell V power Nitro the last two times, so there goes the saving, but I have always got slightly better mpg out of that fuel - never enough to do more than cover the pump price, perhaps even less than that, but the car seems to like it.

[LeeG]

As I understand it, batteries are affected by cold weather too.

The power they give out reduces, therefore the petrol engine is used more.

I have certainly noticed this. During the summer I could easily coast around 40-45 mph on flat roads staying in EV mode. In the colder weather, it would be around 35-40 mph.

Still, I'm happy as consumption is better than my previous IS250 SEL.