Wow - ambient external temperature REALLY matters for MPG

John1701a lives in Minnesota, so you can easily guess when it is cold versus when it is hot.
http://john1701a.com/prius/documents/Prius-2001_MPG_Graphs_Lifetime.pdf

 

Okay, first because of the auto shutter system on Gen 4, it may not be needed. Will evaluate and maybe try when weather turns in the fall.
Here is the what I did. Hardware stores sell black foam sections with a slit for installing on 3/4 inch hot water supply pipes in homes. Purchase one six or eight foot section (about $2) and measure the lower grille openings (this is for pre Gen 4 as have not tried on Gen 4) and cut sections of the foam to fit the openings. Then install by pushing slit portion over the horizontal rib of grille. Install when Temperatures are regularly 50 degrees F or lower and remove in spring when temperatures get above 50 degrees F regularly. The first winter I drove my 2009 without these and avg. 46 - 48 MPG. The second winter with these and avg. 50 -50.5 MPG. So for &2 try it.

 

Yes, grill block is likely pointless with the 2016.

 

In most if not all EU countries you are not allowed to pass to the right, only to the left (UK on the other side, of course).
The max. speed limit is anything between 110 and 130 on highways in all EU countries.
The only exception is of course Germany, where:

1. you cannot pass to the right and have to keep right at all times (unfortunately they are slowly learning to not do it and keep left when overtaking nobody...)
2. the advised speed limit is 130km/h, unless otherwise noted, hence...
3. ...you are allowed to drive as fast as you want, unless otherwise noted, unless you....
4. ...keep a big enough distance from the car preceding you and drive according to weather and traffic conditions.

All this means, that unless there is a speed limit, and the weather and traffic permits it, you can drive as fast you want. And the highways here are flat and made for that in mind. That being said, if you have an accident with anybody, regardless whose fault, and it sorts out you did not have enough distance in front of you from the preceding vehicle to brake in time and avoid collision, or if you are going faster than 130km/h, you have a partial fault and your insurance can and will not pay part of your bill, even if you are not at fault.
Essentially, drive fast as you want, at your own risk (and money).

In practice driving on the autobahns at speeds beyond 130km/h is less and less practical because they are always full *everywhere*, especially close to cities, they are cluttered with road works everywhere, and very often there are speed limits for one or more reasons (tunnels, new tarmac has been laid, bridges, high traffic zones, sound reduction, and so on).
I was on a 2500km road trip from Munich, around the norther part of Germany. The cases in which I could drive "as fast as I wanted" were very few and far apart. Not really worth the hassle. Surely it is nice and "efficient" (time wise) to be able to drive at 140/150km/h (roads and cars allow us today to do so in safety), but otherwise, I'd rather have nice pleasant traffic at 130km/h or even less, and more fluid and be able to pass on the right, than the stressful chaos I see ever more on the streets. Not including the "Facebook" drivers, looking more at the phone and distracted by who knows what, than looking at the street. And not considering those who keep on the left lane "just because".
I'd rather go 330km/h on a high speed train - more fun, more relaxing, more environmental friendly, faster. Unfortunately not many of those here in Germany, the car manufacturer's lobbies, horrible Deutsche Bahn, and the "dream" of driving fast and being "free" do not help.
France, Italy and Spain fare quite well in high speed trains and offer the longest and biggest high speed train networks in the world, after China and possibly Japan.

 

Pakitt, thanks for the very interesting post.

 

If speeds around 130 km/hr are advised, it's kinda sad: that's well into the zone where fuel economy suffers.

 

Well, nothing prevents one to drive slower, say at 110km/h. And some do.
But 130km/h is a speed most find already too slow, not just in Germany and it was set up at a time where environment and fuel consumption were not that important. Rather safety. In Italy there were no speed limits on the highways "autostrada" till the late 70s. And when one traffic minister imposed 110 km/h on the entire network, there was an uproar of protests.
In Switzerland the speed limit is 120km/h and I'd say most follow it, also because there are cameras everywhere to fine you. Driving there in a flow of cars driving all at the same speed is more relaxing than driving in Italy or Germany for sure. And not too slow.

 

I love high-speed trains. The only one I've ever rode was in South Korea, and it was fantastic. Super quiet inside, 300 km/h maximum speed, smooth, and comfortable. That's the way to travel!

 

Fuelly shows my 4 Touring mileage (50.8 overall) increasing month by month. Moreover, I am starting to see 60 MPG on the the trip gauge rather frequently.

Hard to say exactly why, but I am thinking (and hoping) the root cause is the change in ambient temperature. I don't think that my driving style and patterns have changed much. I wish the cars on Fuelly were easier to identify by geographic location,

Anyway, time will tell. Here is how my "sample of 1" from New England is trending:

February (6 Tanks). 48.7 MPG
March (6 Tanks). 50.3 MPG
April (8 Tanks). 51.6 MPG
May (2 Tanks). 54 MPG

For some crude points of reference, here are the average temps for these months where I live:

Feb high 39F low 25F
Mar high 45F low 31F
April high 56F low 41F
May high 66F low 50F

 

The temps have huge impact on the fuel economy. Maybe the Gen 4 the effect will be less drastic, but low temp = low mpg.

 

Looks nice! So as i understand the outside temperature sensor affects the L/100km fuel consumption, even the engine coolant temp. is the same?

 

One part of temperature making a difference is air density changes, which increase significantly the colder it gets, causing more drag on the vehicle. Believe it or not we cyclists also suffer from the problem - so if it affects someone on a bike, it's bound to have a difference on a vehicle...



This is Why You Are Cycling Slower in the Winter (Scroll down to "Higher Winter Air Density")

 

They both play a role. The first depends more on the speed at which you drive on average. The second more on how long you drive a car per trip. The longer the trip, the less the effect of ambient temperature, on average, on fuel consumption. But clearly, the colder the temp, the more the fuel necessary to keep the same things at the same temperature (physics... ).

 

Here's what I do to minimize using the AC.

Before starting, I open all my doors and the hatch and let out as much heat as possible.

Then in eco mode, I point all the vents towards me except the farthest the passenger side vent which I close.
As soon as I turn on the auto climate control, if I hear the fan blow hard I increase the temp until the fan blows low and only 1 or 2 bar shows on the fan speed and the AC turns on and off intermittently just enough to occasionally blow cold air.

Why does this work? Because I don't really need the temp inside the cabin to be 24c/ 74f max to feel comfortable. All I need is the feeling of cold dry air moving directly on my skin.

I can set the temp to 28c / 82f at the beginning of my drive and still feel the occasional slight breeze of cold air on my skin. When the pauses stays too long for my comfort, I click lower on the temp just enough for the pauses to be bearable. Also on long stoplights, I manually turn off the AC if I think it will cause the ICE to fire. Usually by the time I get home (35 to 45 minutes drive), I will not have gone lower than 26c / 78f.

 

When I do use the AC which is seldom - I set it to 78 degrees. That seems to be the point that air feels "cool" and helps me be comfortable.

 

I set the AC to 19C/66F in winter/autumn when the temp is below 65F - I am with a jacket most of the time and well dressed, so I don't need to be any warmer in the car for my mostly "short" 30 mins commute. Longer trips in winter I set it to 22C/71.5F as setting lower will save no fuel as the engine will be going for most of the time.

When the outside temp goes up, I raise the AC to 70-72F/21-22C and leave it there until the outside temps start crawling up to 27C+/80F+, at which point I either decide to raise the AC to 75F/24C or direct the air vents on me - which is not a good idea, especially in the face because I get quickly ear problems/irritations and muscle aches due to the cold air.

I wish that this external temp dependent setting would be automatic, but I doubt it will ever come to be. Also on my Gen3 when the AC goes into recirculation mode (or I set it to that especially in city traffic) the air coming out is always a bit colder. I hope Gen4 fixes that. It is so much colder that sometimes I set the AC 1C/1-2F higher than what I had.

If the car has been sitting long enough to become an oven under the sun, I first open all windows and the trunk to let the hot air out and wait if possible 1 mins or so, then I turn the car on and set the AC to whatever temp I want as per above, remove the recirculation and have the AC run cooler air so that it cools down the vents, the tubing, the system with external air, which is surely cooler than any temperature reached by the car under the sun (car cabins can easily reach 60C/140F or more under the sun - so even if outside is 35C/95F, it is still colder than inside...).
After that I start driving still with all windows open as long as speed is less than 30-40km/h 20-25mph at which point I close all windows and set the AC to auto and let it do its job.
I find the auto setting wanting to recirculate the air from the start quite nonsense as the air inside the car will not be any cooler than the one outside as all the interior is overheated from previous hot air inside. So it is in my opinion more efficient to cool off outside cooler (relatively) air, than the one inside which is getting overheated from all the dark plastic and seats which will keep the heat for a while.
In this way I usually have the AC settle to a normal 1-3 fan speed (depending on whether the sun is shining and the external temp), within 3-4 mins from driving our

 

I use to get better MPG in the winter but not last year. They have done something to the gas down here.

 

Air density also applies in elevation. Air is thinner, and less dense when elevation increases. An electric car at 5,000 feet in elevation with road, speed, and weather conditions all the same will have a longer range at 5,000 feet than at sea level...

 

Would a summer fuel blend also improve your fuel economy? You started the thread in April which was still winter for Minnesota so I bet they still had winter fuel blends. Likely you're seeing 70 mpg with warm temperatures and summer fuel blends, right?