Mileage declining ... must be winter?

happens every year. takes ice longer to warm up and it runs more to stay at operating temp even when you don't need it. if you run the heater, that causes the ice to cool faster and run more as well. in my gen II, i used to get 65 spring and fall, 60 in summer (a/c) and 55 in winter.

 

Why mileage gets worse in winter | PriusChat

 

Do you have winter tires on your Prius-V? I wonder how much difference it is when you switch to winter tires, non-LRR's....

 

Start grill blocking (lower). I have been doing it for 3 weeks now.

 

I'd suspect beside the direct impact of the above mentioned winter factors, the car's computer shifts it's programming, in a preemptive way. It's monitoring ambient temperature, and likely changing warm up behaviors, how long till it allows idle stop, fast idle rpm, etcetera.

I've noticed on the latest tank it's harder to improve mileage (I'm mostly the weekend driver, make it my mission to raise the mpg), and it's not as good at the outset.

In summer I might get the car with 4.8 liters/100 km showing, and push it down to 4.4. This time of year it's more like 5.2>4.8.

 

What good does this do?

 

Basically, by blocking the lower grill of your car, the air will not cool down the ICE as much letting the engine get up to operating temperature quicker, helping you get better mpg.

Check out this thread:

2010 Prius Grill Blocking strategy | PriusChat

Here is my post:

I just simply cut the pipe insulation to length and cut vertical slits to match the vertical fins of the grill. Then I inserted the pipe insulation around the horizontal fin of the grill. No need for zip ties, tape, velcro, etc.

I have had mine on now for about 3 weeks, since the morning temps have been getting down to the low 40s on some occasions. It's been getting up to about 70* during the day. When I monitor the water temp with my Ultra Gauge it goes to about 200*. It definitely helps my engine warm up quicker and somewhat maintain my mileage as the weather changes.



Read more: http://priuschat.com/threads/2010-prius-grill-blocking-strategy.62556/page-17#ixzz2B0Naa4vR

 

When I took Prius for a long drive, ICE is ON on highway, outside temp was -7C (19F) the computer tried to keep engine temp at 88C (190F).
Now driving in a city I blocked off both Upper and Lower grill and on 16km trip (10mi) it is hard to get the engine over 80C (176F) on major intersections the engine temp can drop by 10C when heater fan is ON
(I have hook up temp gauge to OBDII as well). Notice, how low the battery Voltage is, only 11.93V when engine is OFF and Start on second "position". This temp. 6C (42F) is inside garage.

 

I'm noticing the same thing.
I live in Canada and it's getting cold here.
I'm not surprised by the decline in gas mileage since the engine is running more often in the colder weather.
But I am surprised at how quickly the engine apparently gets up to operating temperature. Even though it's cold, the engine cuts out mere minutes into my drive, which means it must be up to optimum temperature.
The mileage is still quite impressive though. I'm averaging 4.9 L/100 km or or 48 MPG for my American friends!
I must say I like the heated seats and the fact that there is heat (probably from the ceramic heaters) very soon after start up (usually within 30 seconds). This is terrific since it gets to defrosting the windows very quickly.

Loving my Prius V!

 

Here in Minneapolis it's getting colder and I've gone from 49.6 mpg in August to 48.9 right now, and still falling.

I was telling someone at work about this decline and he laughed: "You're disappointed with 48.9 miles per gallon?!?" How true. Still better than 99% of the vehicles on the road.

 

A ScanGage (or similar) will help you keep tabs on coolant temperature. (It's a bit of a head shaker to me why the Prius have no (rudimentary) coolant gage, most any econobox on the road does.) What I've observed wih our car, with a ScanGage:

There are multiple "steps" in the warm-up process. If it's similar to a reg Prius, you'll maybe notice: after the car's been running for a block or two, it will shut of the engine when you stop, but only when you come to a full stop. The car will do this when it's so-so warmed, say to around 120~130 Fahrenheit degrees.

As coolant temperature climbs higher the car will start shutting down the engine while you're rolling, so called "EV Mode". So far I've not paid a lot of attention to the levels, but EV Mode starts to happen when the car's around 165 degrees or higher. Fully warmed is around 190 degrees.

 

^ No thermos on 3r gen. There is an accelerated warm-up strategy though: coolant is warmed by exhaust gasses.

I've had no overheating issues. I keep my blocking on the conservative side, and monitor with ScanGage. A 50% block of the lower grill opening is something you can do without risk of overheating, anytime the temps staying at or below 15C (60~F).

Last weekend I kept an eye the ScanGage on extended in-town driving, never saw coolant temps abouve 175 deg F. And this is with ambient temps hovering around 15C. This has me thinking to increase the lower grill blocking, even with these balmy temps.

 

Here in the PNW, I'm having to work pretty hard to achieve 50 mpg on my daily commute (mostly freeway). I've notice that if the road is dry I can still average 52ish mpg on my 67 mi roundtrip (was getting 54-57 during the warmer temps). With wet roads, I average 48-50 mpg (indicated).

My last tank average was 46.7 mpg (49.2 indicated). That's the worse I've seen in a long time.

 

Saw my worst tank yet when i filled up on monday. 6.1 indicated. back and forth to work cruising at 120kmh every day.

Since then i've put 250km on this tank and and can't break an average of 5.8, driving in Eco mode and at a maximum 105kmh cruising speed on my highway commute and generally trying to take it easy, keep it out of the PWR zone. Ambient temps have dropped this week, averaging around -13*c daytime high since monday so i'm sure that has something to do with it.

For comparison sake I was averaging 5.0L/100km in the summer/fall.

Haven't done any grill blocking. Tire pressures could be low but no warning light yet, and I don't really feel like going outside before work when its 20 below and checking them.

I agree snoopytoo, the heated seats are exquisite.

 

Has anyone tried the seat heaters that plug into the cigarette lighter?
I'd like to think that the power drain from that accessory would be made up by the Prius's battery-regenerative powers without having my mileage taking the hit, and it makes more sense to keep myself warm than to heat the whole interior.

 

I've been tracking mileage for a couple of years now, and see tanks go from mid-to-high 4's in the summer, to mid-to-high 5's in winter. And our winters are nothing like yours. You will take a hit in winter. Easy tweaks are the tire pressures and grill blocking.

I don't know if anyones researched where the inverter cooler is on the v, but it's been suggested to avoid blocking in front of it. Our's is behind the upper grill, and I've blocked the lower grill 100%, left upper grill open. No overheating (watching with ScanGage), with ambient temps between +3 and +10 in our area, mostly around +5~6.

 

I haven't tried those plug in add-on seat heaters but I would assume running the seat heater and lowering the cabin temperature would give you overall better efficiency as you say. I doubt it makes a huge difference though.
I find depending how warm I am dressed the seat heater in the V can get unbearably hot to leave it on the whole trip even when its -20 outside! If I dress just warm enough for the weather I find I can stand the heated seat on for longer. I also find drinking coffee while i'm driving in cold weather I have to keep the cabin temperature low and the seat heater off as I get way too warm.
So my advice, when its cold out, dress really warm and drink coffee while you drive, should be able to manage without using the heated seats or cabin heat at all. Might even have to roll down the windows, haha.