Cars - cold weather

[revjames]

I have noticed a marked reduction in MPGs withn cold weather. My car (53 Rover 45 1.6 petrol manual) was doing 38-45 mpg. But now its gone really cold the figures are much worse - 30 - 35 mpg. Anorak I know, but I log the mileage every time I fill up and work out the maths.

I am used to diesels but cant recall having a difference like this with any car.

 

[Andy™]

do you leave the engine running longer to warm up etc?

cant say ive noticed any difference with my van though

 

[revjames]

nah just jump in and fire it up, then off. Less AC use too so that should improve things.

 

[Apache]

Cheap diesel? Is this just on the one tank?

 

[revjames]

Its a petrol one Patch, its just my last few cars were diesels. wondered if petrols used more in cold weather.

 

[Sidewinder]

Rev,

They will to start as the fuel enrichment (aka choke) is on for longer.

It will also kick in at every start as the ambient is so low, though it will go off quickly.

You will be using the lights, heater & heated rear screen more thus drawing more from the alternator.

This as a start will increase fuel consumption, however the denser cold air will improve efficiency, though IIRC your car uses an air mass flow meter not an air volume flow meter, thus the engine will produce more power in the cold as the denser (more massive) air will allow the system to inject more fuel.

This in turn will increase engine power, thus reducing the throttle openings required.

However, this will also increase the fuelling at idle etc. and if the car is on short journeys will increase the consumption possibly noticeably.

 

[Evans Electric]

Perhaps low gear driving too , in the snow.