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Cold weather fuel consumption


Marcusthehat
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Owned the car since late June, and now just turning 5000 miles, was getting about 55mpg, now getting 45 mpg, with no significent change in driving conditions, other than perhaps fewer longer runs/more shorter journies(where I understood the HEV excelled?) or driving behavoir(def not driving faster or more aggressively), other than lower ambient temps.

So how much does the cold pull back mpg's?

Marcus

P.S.

A couple of  wee observations,

1. the tyre pressure moniter is apparently set very sensitive(and I may adjust this)

2. no low windscreen washer fluid warning?

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Cold weather will adversely affect consumption, plus if using E10 since September, will also contribute a bit to higher consumption.

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It would seem that there is around a 3% reduction in economy with E10 over E5, the Rav4 may excel against other cars on short runs but it will not be better than longer runs in a like for like cars.

Then the lights come on sooner in winter, the heater gets used more and air con to demist the windows and heated seats (model dependent) and also ICE are less efficient in cold weather.

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I was averaging about 47mpg (using E10) Since the colder weather this has dropped to around 37mpg; I've put it down to using the heater (set on ECO in the summer, but now, initially, set on Fast) and heated seats.

This is just from short local runs, I've not done a longer run since the colder weather arrived.

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1 hour ago, Roger_N said:

It would seem that there is around a 3% reduction in economy with E10 over E5

Close ... I believe that there is a reduction of around 2.6% in economy between E0 and E10 - i.e. between pure petrol and 10% ethanol. Obviously our alternative was/is E5 (5% ethanol) so the reduction to E10 will be 'only' 1.3%. So there is indeed a small reduction in economy, but it is rather small compared with other factors and variations ...

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The car is spec’d for E10 so I’d have assumed that this was used for the type approval rather than E0 or E5?

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2 hours ago, Marcusthehat said:

was getting about 55mpg, now getting 45 mpg

How are you measuring these figures? The good old brim-to-brim method is still the most reliable ...

Trip by trip my results vary wildly. Economy for a short trip on a cold day is appalling - i.e. the car can easily report something as low as 30 mpg since the car has spent a large proportion of the journey getting up to temperature. Or gentle A or B road trips I can easily get into the 50's - best recorded being 71mpg. Once I stick the car in cruise at 70mph on a motorway it'll return 47mpg (give or take).

As above, cold weather will hit economy as you start switching on more ancillary services to keep warm and see where you are going but I would expect that hit to be more than 2-3 mpg ...

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3 minutes ago, ernieb said:

The car is spec’d for E10 so I’d have assumed that this was used for the type approval rather than E0 or E5?

E0 doesn't exist so that's wholly irrelevant but the simple fact is that petrol has a higher calorific value than ethanol so you get a better bang for your buck with petrol than you do ethanol. So, irrespective of how the car is spec'd you'd do better with pure petrol than with pure ethanol (assuming that the car would run happily that is! 🙂 ).

Since the car actively monitors how the engine is running it will automatically adjust for the quality of the fuel and the amount of ethanol it contains (up to the 10% limit at least). So the driver shouldn't notice any difference in driveability etc. but might just about detect a difference in fuel consumption if you can measure that accurately enough.

In terms of type approval measurements, I've no idea whether they used E5, E10 or a specifically blended type approval formula. And for the sake of a couple of percent in 47 mpg I seriously couldn't care - the answer's still going to come out somewhere between 46 and 48 ... 😉

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On my Corolla it's +5% more fuel in winter. I mostly drive to work and back , same way, same driving style and still on summer tires 🙂 

On longer runs have the same consumption like in sommer. It's probably the initial engine warm up that eats all the extra fuel.

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In over 45 years driving an average of 20k miles annually and in over 50 different cars in that time (petrol, diesel, PHEV) I would expect typically 5-10% increase in fuel used in winter. Extreme cold can push that to 20% or more but those winters are now banned by global warming. In addition various legislative changes to fuel and emmission regulations have also increased fuel consumption, not least of which the need for such as DPF’s and E additives to create E5 and E10 fuel. Talking to my local spannerman this morning and he is telling customers who will listen and intend keeping their cars a long time to spend the extra on premium fuels. He sees the benefits when checking exhaust emmissions at MOT and less fuel system and engine wear. I always use the likes of Vpower or equivalent fuel and will do so in the RAV. 

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E10 does not even smell like petrol, E5 still does a bit. The higher the ethanol content is the dryer the fuel is which means higher friction and energy lost as extra heat and wear on the all metal parts, higher corrosion levels on bear metals in the engine, higher rate of thinning the oil too, all in all if you love your car better don’t use it at all. I tried few times and my hybrid simply dislike it a lot, engine became immediately louder and less responsive, it felt like there is no oil inside and tyres are half way down in psi., since I do a few full tanks per week I start using exclusively Tesco momentum 99 E5 from a local supermarket and the car drives better than new., plus the price is the same as E10 95 from other garages. 👍

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I don’t use a great deal of fuel in my PHEV so maybe a case for looking at the premium fuels?

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33 minutes ago, ernieb said:

I don’t use a great deal of fuel in my PHEV so maybe a case for looking at the premium fuels?

I will only be using premium fuel. The extra £6-7 a fill up is a fraction of the cost if the engine suffers premature wear or damage. From my 15 years of using premium fuels You will find when running in ICE mode the engine will be smoother, slightly more spritely, quieter and better mpg. 

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37 minutes ago, ernieb said:

I don’t use a great deal of fuel in my PHEV so maybe a case for looking at the premium fuels?

That's what I do, my Corolla has about 20% better fuel economy then previous car, so I don't mind buying premium, still saving money.

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I am judging from the mpg figure centre of the dash, plus the energy use/fuel consumption from the infomation unit.

All in all only indictive, but a clear 55mpg  to 45mpg reduction.

So about 20% worse 

Still acceptable though.

I tried and failed to use the "fuelly" app. I found it most awkward and uncooperative. I am however more than a little techno-illiterate.

cheers all,

Marcus

 

 

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The cold weather has dropped me by about 2-3mpg.

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TBH even 45mpg is damn good from a 2 tonne SUV. About what we get with our SEAT Arona with its 95 horse 3 pot  engine. 

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36 minutes ago, Marcusthehat said:

I tried and failed to use the "fuelly" app. I found it most awkward and uncooperative. I am however more than a little techno-illiterate.

I failed at the first attempt with Fuelly, but got it right at a 2nd attempt. You could try www.spritmonitor.de it does the same, but they are based in Germany rather than the US. It's what I use.

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Winter has always hit the more efficient cars the most - Even when I had my old Mk1 diesel I found I could get half-way to work with the Engine Cold indicator still lit, and the engine would be a bit laggy until it warmed up; Hybrids get hit hard too as they don't run the engines all the time so they struggle to stay at the most efficient temperature, and also they have to supply heat to the cabin.

If you are really worried about mpg, the easiest thing to improve it is to turn the HVAC off until the engine gets to operating temperature, and turn it off when stationary. This is not a great solution tho' as you'll be freezing your nuts off when it gets properly wintery!

Try to avoid short journeys too as the car will never get hot if you do lots of short journeys. One thing I've found that can help is to be a bit brisker with the acceleration as that helps put a bit more heat into the system to get it up to temperature - I've been finding if I go as high up the Eco band as I can, without going into the Power band, that helps the engine warm up faster while still staying quite efficient.

 

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To improve the heater in the PHEV switch from ECO to Normal and, I think this is true in the HEV, this runs the HVAC system harder? I’ve found when it’s cold that I start the car in Normal and after a short while I can switch back to ECO. 

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Normal mode for everything works the best all the times. 👍

Now about our hybrids and the cold weather, there is one more thing to point out and why I think is better to keep climate control ON set at room temperature around 20C°. Our cars has an air cooled batteries that air comes from the cabin. Battery chemistry and what happens inside likes that 20C° for maximum performance and long life and so the car ecu+bms decides how much power to drought out from the Battery in any one moment and the Battery temperature dictate how much or how little. When is too cold or too hot even with good amount of battery charge the car may prefer to let the ice work harder and use very little battery power just to preserve its battery health and longevity. You can trick the car with turning hvac off when freezing cold and drive around town and you will notice how the car is still running its ice even though it has got to its operating temperature reached. That’s why Toyota recommend to use heating in winter and ac in summer to accommodate hybrid battery best temperature environment.
🔋👍 

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There are options with the PHEV to heat and cool the traction Battery obviously takes some energy but will maximise the Battery performance and life.

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And if fuel economy in winter is such a big concern on a £40k plus car one has to question whether the car is affordable in the first place. It is a simple fact of life more energy is required in cold weather. 

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Correct, I keep my car in ready mode for hours during cold winter nights for heating and e power, it does use more fuel but then I drive a bit slower and compensate for the extra litres of fuel used while stationary, the good thing is that my batteries gets proper charge and so far they still works fine after many years, the bad thing is a bit of more oil consumption but that’s not much more than a cup of tea 👍 When cold we use more energy, we pay more, nothing new here, all other cars including full ev will be the same. 🙂

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  • 4 weeks later...

Filled the car with E5 99 octane at Tesco this morning and noticed that it is 5p per litre more than E10, the price difference used to be 7p.  I wonder if sales of E5 have dropped recently due to the increasing price of fuel and they are trying to get custom back.  

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