Colder weather lower mpg

[Cbatoday]

Have noticed as the temps start to lower the mpg has dropped slightly on the 1.8 hybrid 

Guess the petrol engine needs longer to warm up and faster to cool down

Still it's at 67mpg for most of my town driving

[AndrueC]

Yep, mine has dropped. The dash isn't reaching 60 mpg at the moment so I'm probably only getting around 55 mpg. Battery is also noticeably less keen to help out and doesn't last as long.

[Chippy01]

Yep. Lower temperatures, head winds, and wet roads all take their toll on your mpg.

The same things effect all vehicles to some degree, but it's hybrid drivers who track their fuel usage closely that notice it more.

[PeteB]

and while we Hybrid drivers have a lot of advantages, one slight disadvantage is that we may be running the petrol engine some of the time just to warm up the cabin.

[TonyHSD]

That’s exactly what I do in colder nights, sometimes I keep the car in ready mode for hours, mpg down from average 60 in summer to 50 in winter, still happy tho, rain affects a lot too. 

[Cbatoday]

Suppose it also with the heater, wipers, lights, heated seats and various other items we used in winter over summer that increase the amount of energy required from the vehicle that causes the mpg to drop

Still it could be worse with an all electric vehicle which would increase your range anxiety.

[Gerg]

When the weather turns a bit cooler then, depending on how important the mpg figure is to you, you could try googling 'Prius grill blocking', or take a look at this link.  On the gen 4 Prius, Toyota has helpfully fitted an automatic radiator block behind the bumper grille, with a view to increasing economy.  On previous generations of Prius, Auris and almost certainly the new Corolla, they don't do this. 

As a d-i-y stand-in for that, the most popular setup involves the clipping of the pre-formed, foam pipe insulation to the horizontal grille slats, to reduce the intake area to the radiators and thence the speed that the engine cools down.  So, especially useful when the car spends much time in EV mode.  Some care is required to leave airflow to the inverter radiator, which since the advent of the 1.8 HSD has always been the top front radiator - for that one cooler is better.

On the other hand, your Corolla is a perhaps bit new to be experimenting with it.

This is not for everyone, obviously.

[rafletcher]

Isn't that what a thermostat does? Opens to allow circulation around the radiator when the engine is at operating temp, and closes when the return flow is too cold? 😉.   Perhaps at very low temps they might have some use, but not in the UK generally I think.  Also cold air is denser, so more taken in every stroke,  and more power per stroke produced.

IMO it's heating/lights/heated seats etc. that make the most difference, plus idling to de-mist/ice. And perhaps the denser air increases drag as well, as do wet roads. 

[Catlover]

Generally, batteries don’t like the cold, they perform less efficiently, therefore one reason why hybrid mpg figures take a dive in winter.  Add to that, the engine takes longer to warm up and quicker to cool down, thus meaning the computer tells it to fire up more, then, again mpg goes down. Then you have ancillaries like cabin warmth, demisters, heated seats, lights, wipers etc, so mpg again takes a hit.

In the wife’s 2010 Auris Hybrid, and my Gen4 Prius, last year we noted a 8-10mpg drop. Once the outside temperature drops below 10 degree I am expecting a drop in mpg.

[Gerg]

1 hour ago, rafletcher said:

IMO it's heating/lights/heated seats etc.

Yes, there's no question that the above are the major negative influences on fuel consumption in winter, but there is not much you can do about those, apart from dressing up warm when driving the car so you don't need the heater so high.......

In a 'normal' car the engine will be running anyway, so some of the engine heat produced is dumped into the air as waste - once the engine has warmed up there is generally a surplus of heat in a normal car, (although on some small diesels this can be a bit marginal in winter).  

As hybrid engine doesn't need to run all the time to move the car, so the situation changes a bit!  You can be running the engine just to warm the cabin - that engine heat is a valuable resource instead of waste - the supply is more limited because the whole system is more efficient.  The engine in its entirety is cooled by the outside surfaces of the engine as well as the radiator.  The radiator is controlled by the thermostat, but the other heat loss isn't - when the radiator is shut off the engine is still losing heat from elsewhere.

It's not an idea that makes much sense at first.

So maintaining engine heat by reducing underbonnet heat-loss can be a small economy win.  

Oh, and you get a little less salty road-crud going into your radiators.....

[PeteB]

On 10/18/2019 at 11:09 AM, Gerg said:

So maintaining engine heat by reducing underbonnet heat-loss can be a small economy win.

... which is exactly why the latest Prius (2016 onward) has a louvred lower grille which opens and shuts according to the cooling needs of the car.  According to the Toyota blurb at the launch, it also aids aerodynamics when closed.

[Abernus]

On 10/17/2019 at 4:23 PM, Cbatoday said:

Have noticed as the temps start to lower the mpg has dropped slightly on the 1.8 hybrid 

Guess the petrol engine needs longer to warm up and faster to cool down

Still it's at 67mpg for most of my town driving

If only I was getting 67mpg on mine! I do a combination of City and Motorway driving and during summer the best I got was 58.5mpg. However yes as the temp drops so does the mpg. I am down to 58.3mpg now.

[AndrueC]

Mine is almost managing to show 60 on the dashboard but driving on wet roads is preventing it. I don't know what the actual mpg is yet but I'm still thinking around 55 mpg.

[Timmon]

I normally get 52 to 54 mpg, but down to 48 now😭. Having said that, a trip to Towcester, Daventry, then home via Banbury , got me back to 53 today, even with wipers and headlights on! Temperature is back up today, tomorrow onwards colder they say. I wonder what mpg January and Feb will bring....

[AndrueC]

I went out to Kettering and back while my Sat Nav updated. Thought I'd pop back and see how the old dump had changed since I lived there. The answer, funnily enough, is that Kettering has changed a lot since the 1980s.A ridiculous number of houses been built around the southern/eastern edges. My old house used to be on the outskirts and it's not any more.

[PeteB]

27 minutes ago, AndrueC said:

...Kettering has changed a lot since the 1980s...

I lived in Addlestone, Surrey until 1987 and last visited at least 15 years ago - it was almost unrecognisable then!  The town centre had been massively redeveloped (bus depot was a housing estate) and several redevelopments during my teens and 20s had been redeveloped again on an even larger scale.

If I had been teleported there and any signs with the town name covered up, it would have taken me hours to work out I was in the town where I spent my first 30 years!

[Timmon]

41 minutes ago, AndrueC said:

I went out to Kettering and back while my Sat Nav updated. Thought I'd pop back and see how the old dump had changed since I lived there. The answer, funnily enough, is that Kettering has changed a lot since the 1980s.A ridiculous number of houses been built around the southern/eastern edges. My old house used to be on the outskirts and it's not any more.

I must update my sat nav now. I did not do it while out and about as I had to stop a few times, which would have messed it up. Any noticeable improvements with the update, or is it just a routine map change, that we may or may not notice? I am wondering if we will see anything added to the Estore at some point, that we can download.

[AndrueC]

19 minutes ago, Timmon said:

I must update my sat nav now. I did not do it while out and about as I had to stop a few times, which would have messed it up. Any noticeable improvements with the update, or is it just a routine map change, that we may or may not notice? I am wondering if we will see anything added to the Estore at some point, that we can download.

No obvious changes but bluetooth connectivity stopped for the last twenty minutes which suggests more than a map update.

[AndrueC]

Hmm. 56 mpg it turns out.

[TonyHSD]

Just changed summer to winter tyres and drop in mpg straight away, no greetings for excellent efficiency on screen anymore 👍

[PeteB]

Monday last week my dealer swapped my original Bridgestone summer tyres for Vredstein all-seasons.

Can't say my mpg has dropped any more than it had already, but unlike the winter tyres I used on my lest two cars the noise level hasn't increased noticeably, which is good news.

I plan to have them swapped twice a year until the summer tyres reach 3mm then I'll keep the all-seasons on all year.

[AndrueC]

Last night was odd as well. A truly rare event in that I was able to drive from my office to the other side of the M40 without stopping and mostly at 'full speed' (between 40 and 50 mph). Consequently the Battery hardly did anything for the first two miles. When I got home the car was showing a dismal 55.4 mpg if that equates to an actual 50 mpg that's horrible.

It was nice to get home in a record 19 minutes but intriguing if not having the Battery helping out 'costs' me extra fuel. I suppose the higher speed could be the reason.