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Nicolai

Poor And I Mean Poor Mpg, And Tyre Pressures In Winter Tyres

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Ok, to be fair I do a lot of really short runs and the temp. has been around -5 to 0 degrees celsius lately. Done 250 km on current tank: half full and an indicated mpg of 37.3 mpg. :dontgetit: Majority is town drown driving. Use heating for all windows/wing mirrors often. On a 5 mile run to the grocery store it did return an indicated of 46.6 mpg.

In the late summer on a long A-road trip to my parents' it returned an indicated of 67.8. I got my winter tyres around late november/beginning of december and haven't checked tyre pressure once (too damn cold). What pressure should I go for? the standard eco pressure or should I add a little extra due to the cold weather?

The user inhere (forgot name) with blue Auris HSD 2012 or '13, according to fully, has an average of 60 MPG. How he does it is really beyond me! I need to add a tank in my fully stats with that added, average is probably 50 or 49 mpg!

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Short runs don't do cars any good on petrol, I travel 30 miles a day to work in total so my yaris (and soon to be an Aygo) always gets a good run, so the petrol lasts about a fortnight on a full fill up bar the odd major road trip (1 hour +) which is only once a year if that. The winter tyres I have on the Yaris don't seem to make any difference petrol wise in the winter either.

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Fuel figures fall in cold weather especially it seams diesels.

Tyres should be run on standard pressures, winter tyres are made for the cold so no extra pressure the compounds are more rubber in order to retain the proper flex in +7 or below temps where standard rubber is harder and takes longer to warm unlike the winter tyre that warms up faster with softer compound.

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Short journeys in the cold are very punishing for diesel and hybrid cars; Even tiny 1L petrol engines don't take such a big hit!

My dad can quarter the mpg his Focus gets this time of year if he only drives short distances. I can get halfway to work before my ickle Yaris' cold-engine light goes out on a properly cold day...!

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Ok, to be fair I do a lot of really short runs and the temp. has been around -5 to 0 degrees celsius lately. Done 250 km on current tank: half full and an indicated mpg of 37.3 mpg. :dontgetit: Majority is town drown driving. Use heating for all windows/wing mirrors often. On a 5 mile run to the grocery store it did return an indicated of 46.6 mpg. In the late summer on a long A-road trip to my parents' it returned an indicated of 67.8. I got my winter tyres around late november/beginning of december and haven't checked tyre pressure once (too damn cold). What pressure should I go for? the standard eco pressure or should I add a little extra due to the cold weather? The user inhere (forgot name) with blue Auris HSD 2012 or '13, according to fully, has an average of 60 MPG. How he does it is really beyond me! I need to add a tank in my fully stats with that added, average is probably 50 or 49 mpg!

Thumb rule is that every -10 degrees drop the tyre pressures by 0.1. I've usually put 0.5 over the recommended pressures.

And we Finns know about winter driving ;)

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Well, I thought I should be worried at first but I'm only 3mpg behind and I've had a lot more fill ups to get more of an average over time.

Either way, so much for Mr T's 70+mpg. Ha!

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My last tankful was around 36 mpg all short 3 mile journeys, cold weather and heater on 23C all the time. As I'm getting low mpgs anyway this time of year I don't resort to any hyper-miling techniques at all, I just drive it like a normal car and I still get 20-30% better fuel economy than the Mk4 Mondeo TDCi Auto I had 4 years ago.

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If you want to get the numbers up, you could waste fuel by taking it on a random joyride :D :naughty:

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When the engine's running all the time to warm up you'll pretty much be getting the fuel economy of a 1.8 petrol automatic. Actually, probably not that bad. A 1.8 auto petrol would probably be getting 26 mpg in town, so 37 mpg still ain't that bad.

I know from my car that in summer it will have warmed up enough to switch the engine off after about half a mile, leaving the other 3.5 miles to run efficiently, whereas in winter it sometimes hasn't warmed up by the time I get to work.

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If I don't need to demist the windows, I have started switching off the auto climate control, leaving the car in eco mode and just using the seat heaters to stay comfortable on cold mornings. Once I'm out of town and on stretches of dual carriageway, the engine warms up quicker and then I turn the climate control on.

That has gotten me a few more mpg than normal on the trip computer going work.

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Ok, to be fair I do a lot of really short runs and the temp. has been around -5 to 0 degrees celsius lately. Done 250 km on current tank: half full and an indicated mpg of 37.3 mpg. :dontgetit: Majority is town drown driving. Use heating for all windows/wing mirrors often. On a 5 mile run to the grocery store it did return an indicated of 46.6 mpg.

That's good for such a short trip in those conditions. The only source of heat for you and the car is petrol (unless the sun comes out). If the temps are that low for some time, you can look at grill blocking (stops the engine cooling down quickly) and perhaps a block heater (warm the engine up before you start in the morning). Are you able to garage the car overnight?

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Ok, to be fair I do a lot of really short runs and the temp. has been around -5 to 0 degrees celsius lately. Done 250 km on current tank: half full and an indicated mpg of 37.3 mpg. :dontgetit: Majority is town drown driving. Use heating for all windows/wing mirrors often. On a 5 mile run to the grocery store it did return an indicated of 46.6 mpg.

That's good for such a short trip in those conditions. The only source of heat for you and the car is petrol (unless the sun comes out). If the temps are that low for some time, you can look at grill blocking (stops the engine cooling down quickly) and perhaps a block heater (warm the engine up before you start in the morning). Are you able to garage the car overnight?

Unfortunately, we don't have a garage. Our house is a fairly small 108 squaremeter (1162 spuarefeet) terraced house with a small driveway. I thought block heaters were primarily for diesels and, whilst not healthy for any car, I was under the impression that HSD handles cold starts better. These days I could do with a temperature gauge. I just drive the car like I would normally. Including accelerations in the PWR section.

With HSD is it better with smooth slow access compared to swift "get up to speed" ones (for economy, I mean)? I can't figure it out. Some say yes and other users have found that getting up to speed quickly i more economical.

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Nicolai,

The engine is working at it's most efficiently in the top half of the green section of the Eco guage. Having seen the engine performance graphs, it makes practically no difference which part of that upper green section you are in - The engine is super efficient for all of that range. When the needle turns red though, the engine has to change it's mode of operation and opens up some valves to suck through more fuel/air - at that point it becomes far less efficient.

In the lower-half of the green section on the Eco guage the engine is using practically zero fuel.. but it is also producing very little power. The engine is actually operating more efficiently (in terms of KWs per Litre) in the upper half of the green section where it is producing lots of KWs for every sip of fuel.

I understand that it is best to accellerate with the needle at the very top of the green section. (There is an audible difference to the engine sound when the valves open up and the needle goes red), and then glide along once I reach my desired speed.

HTH

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Hi Fecn

Thank you for your post. The problem is if feel that around town, there's virtually no accel power in the green zone....

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Maybe the Auris HSD isn't the car for you Nicolai?

I've had a look through your posts and they're all pretty much negative about the Auris HSD. You say the steering has no feel, the plastics inside are cheap looking, the mpg in winter doesn't meet your approval. I have struggled to find a positive comment!

I have had problems with my Prius and these have been reported. I also do like the fabulous ride, comfort and fuel economy and have reported that too and hopefully that gives a balance of the good and bad of my particularly unreliable Prius.

But seriously, if you are this unhappy with your car, and from reading your early posts you were not entirely happy with the Auris BEFORE you bought one, one has to wonder if it's just not for you.

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Hi Fecn

Thank you for your post. The problem is if feel that around town, there's virtually no accel power in the green zone....

I guess that depends on your town. Around my town I find that the speed of the creep function vastly exceeds the speed of the heavily congested traffic so I keep having use the brakes (never once touching the accelerator). What I would give to be able to accellerate at the top of the green zone.. Phew.. that would take me up to crazy speeds of twenty-something miles per hour - As it is it takes me around 2.5 miles to get up to 30 mph... but then it takes the same time for the 6.7 litre V8 in front of me to reach that speed too.

Once I get out of town though, then yes... either I let that 6.7 litre V8 leave me in the dust, or I push my needle into the red zone so that I can keep up (whilst still using far far less fuel than everything else around).

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Hi Fecn

Thank you for your post. The problem is if feel that around town, there's virtually no accel power in the green zone....

I think you may have answered your own question about poor fuel consumption.

Try and be a little more relaxed in your driving style, accelerate by all means when you can, but try and anticipate ahead, there is no point accelerating then having to brake hard after a few metres,

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Like everyone I guess, I've noticed the mpg worsen as the weather gets colder. My tank average on my Prius+ has dropped from around 53 (computer) to 46 over the same type of journeys since the summer. However, diesel estate cars of similar size in the past (passat bluemotion, mondeo econetic) where only giving around 38mpg over the same journeys so the hybrid is still much better. I also have recently had a week and a half in a 1.2 petrol fiesta whilst my Prius+ was in the bodyshop (a separate storey) and over the same journeys the little fiesta only managed 36 mpg (computer) so even in the winter the big Prius+ is 10mpg better than a 1.2 fiesta!

One thing I have found is that the Prius+ is affected badly by strong head winds. Last weekend I went London and back and due to the way the wind was changing I had a strong headwind both ways. Over the 230 mile round trip my average mpg was only 41mpg and that was only doing 75 on the motorway. I imagine that the high profile means that it has a penalty as drag coeficient is alway multipled by cross sectional area to give the actual drag.

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Maybe the Auris HSD isn't the car for you Nicolai?

I've had a look through your posts and they're all pretty much negative about the Auris HSD. You say the steering has no feel, the plastics inside are cheap looking, the mpg in winter doesn't meet your approval. I have struggled to find a positive comment!

But seriously, if you are this unhappy with your car, and from reading your early posts you were not entirely happy with the Auris BEFORE you bought one, one has to wonder if it's just not for you.

It took Nicolai over a year and numerous posts to decide on the Auris HSD - don't think some members could cope with a similar exercise if he were to change so soon.

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Have had below zero and snow here in my part of Sweden now for a couple of weeks. I have also noticed a drop in mpg for my Auris Hybrid, but I must say not as much as I had expected. It's seems it's just the really short trips where there is a really noticeable difference. It takes longer for everything to warm up, I guess.

Also I must say that I'm pretty impressed how the car handles in winter / snow. I feel as safe in this car as I did in my previous 4WD SUV. Of course, real winter tyres makes all the difference.

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I am fortunate to have a commute which is ideally suited to hybrid driving and I am also prepared to drive - within reason - in a manner which improves economy at the expense of speed. As a result I have only this week just dipped below 70mpg as my average on Fuelly having run the car since May. With the relatively mild winter, the difference between my worst winter weekly fill (65mpg) and best summer fill (76mpg) is 11mpg. I would expect a greater differential if we ever get a full week of much colder weather - I struggled to crack 60mpg in my wife's Auris HSD last year when it was really cold.

Here's the relevant bit though: If I only did journeys like those described by Nicolai, I would be getting roughly the same mpg as he is. The first two miles of my journey home each day is through a congested town up a hill. At the end of those two miles, I will regularly see a display on the MFD of lower than 30mpg at this time of year and that's in weather which isn't as cold as he is experiencing. Adopting aceshigh's approach of turning the heater off until the engine is warm does allow milkfloat mode to operate earlier but even then this only nets maybe 4-5mpg gain over the same distance. Even on my journey out in the morning which is a clear country road, after a couple of miles I will be lucky to see over 40mpg on the MFD.

Short journeys will always utterly 'destroy' fuel economy if compared to longer trips. Hybrids are no different from any other car in this respect - they are at their least efficient when cold and in stop/start traffic which requires constant acceleration and slowing down. Unfortunately, their reputation as 'city cars' probably leads owners to expect near-magical capabilities when driving in town!

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The heater is useless at this time of year for the first mile or so. It only blows cold air and uses power, so why not turn it off ? This is true of any car by the way.Unless you really need the dual zone climate control turn that off as well and just run it as a normal heater, switching to climate control if things get misty.

I live on a mile long steep hill and for the the downward run the clock shows 60 mpg from cold, and when going the other way 22 mpg at the end of the mile. No surprises there. After a long run > 10 miles I gain or lose about 1 mpg on that same hill with a warm car. Most of my journeys are 5-15 miles long and I average a true 51 mpg against a computer figure of 55 mpg ( 8% optimistic computer ).

I don't often hit traffic but when I do have to crawl around town my fuel consumption decreases remarkably with computer figures regularly rising well above 60 and sometimes up to 70 mpg. There is no doubt that this car is built to crawl around commuter land and is probably the reason why we see such widely varying figures from people. Much depends on where you take your car. Heavy traffic is good, the open country is bad for fuel consumption, bad being a relative term of course. Oddly enough this is the opposite of what one would expect from a normal car.

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Bad? Define bad? On the open road I'd get 70-75mpg in summer. In a 12 month average over 34,000 miles, my town fuel economy was 49.9 mpg. Much better than a petrol or diesel in those exact circumstances, but still this is opposite to your experience.

For a petrol automatic car of the size of the Prius, that's good going whatever though. There are some cars that get better mpg's, but are smaller or slower or manual or all of these. I think as a good all round the Toyota hybrid system takes some beating.

I think best mpg's it depends mainly on traffic conditions, length of those conditions, the weather, wet or dry roads and how the traffic is.

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I also get the best mpgs on the open country roads GC.

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