Colder weather has zapped my mileage to 44mpg

Thanks, very useful information. Do you get that half inch foam insulation in home improvement stores? Is it like a foam pipe? Do you use anything to stick them to the grill or just physically push them until they fit?

 

Yes, any hardware or home improvement store should have it. The half inch diameter is the inside diameter for the pipe as the outside is bigger and fits the grill very well. No need for the stick on kind, as it probably makes a mess and I found it is unnecessary. It is pre-slit length wise and I just had to cut it to length and then make the cross cuts maybe 40%-50% of the way thru the form to match the vertical supports in the grill. It pressure fits in nicely, is hard to really notice unless you're looking for it, and the oncoming air keeps it in place. Search for 2010 grill blocking to read more.

Since I installed my SG a week ago, driving in the 20s and 30s, in the city on short trips the water temp doesn't even get close to 190. On the highway it did but not over. Others on this site probably have more highway miles with blocking and a SG and can report on it.

 

ya, my commutes, 7 miles, speeds at 40 mph or below. in the morning its a straight cruise pretty much. no traffic to speak of. lots of lights but all but 3 are easy to time. yesterday, most of the trip water temps were in the 130-145 range. top temp was around 154. normally it rides right at 175-190.

i block 100% bottom, 75% top. at those temps, i dont see any problem doing 100%. i seriously doubt that the inverter or anything else for that matter will be overly warm when it that cold.

 

I feel your pain ma bratha ... I'm down to 58.5 to 60 ish per tank, the past 2 tank fills



You will get better as the months march on into years. It will come with learning the tricks, and practice.

.

 

You should be able to pick up the foam pieces at any hardware store in about 6-foot lengths (I got mine at Home Depot). The foam comes with a single 6-foot cut along its length, and it's originally designed to slip around the outside of a 1/2 inch diameter pipe to insulate it. It's cheap, under $2.00 per piece.

Along with the existing 6-foot-long cut, use a knife to add a second 6-foot-long cut directly opposite to the existing one; you will end up with two 6-foot long U-shaped pieces of foam. Take them to the front of the car, cut them to length, and carefully pressure fit them between each of the four open areas within the bottom grill. You can repeat this process for the two slots along the top area of the grill that route air for the inverter part of the radiator, although some people feel that you should leave one of these two slots open just to make sure that the inverter doesn't overheat (and the ScanGauge cannot monitor this temperature).

The foam pieces will fit just in front of multiple existing plastic interconnect pieces that are recessed and and are used to hold the plastic grill together. These recessed plastic pieces are useful in that they provide a back support for the foam so that air pressure doesn't push the foam straight through while you are driving. Some people cut slots in the back of the foam to line up with the plastic pieces so that the foam will recess back a bit further back; I didn't bother with this.

I added the foam on my car, but then I became concerned that I might be overheating, so I purchased and installed a ScanGauge. I suggest that you might consider purchasing the ScanGauge before you do this; you may not need it but it is good to have it just for your own piece of mind. Besides the water temperature, the ScanGauge is also useful for tracking the 12-V battery voltage, RPM, and the MPG from the ScanGauge's perspective. It's dead easy to install -- you just double-side tape it to the top of your steering column and connect the wire to the ODB-II port directly below.

 

Superb! That's why I keep coming here. People, who I never me before, are kind enough to take their precious time to elaborate such a detailed explanation like this one. Very much appreciated!

I will do 2-4 more trips in the cold to see how much bitter conditions will impact my MPG. This is the perfect time for bitterly cold strong winds in the Midwest. After that, think I may try blocking the grills and maybe Santa will help me out with the scangauge.

One more question. Do you pressure fit the concave or convex face of the U-shaped foam piece to the grill?

Thanks again... cheers...

 

Was getting 51-53 mpg in the summer. Got to around 48-52 in the fall, and now around 45-47. Seattle has been cold the past couple weeks, lows at the 10s, and highs in the low 30s.

 

I've always done and seen the concave face inserted toward the car, Indy, fwiw. Absent the SGII, just take out the blocking as spring approaches. No way a lower block will overheat anything in winter. Unless your radiator gets blocked with wheat chaff (oh, wait, I'm the one in KS).

 

A lot depends on how you look at it. The 20% loss of mileage by the Prius in winter represents just a portion of the fuel wasted by other cars year round. So yes, the Prius takes a hit in cold weather but still runs more efficiently than almost anything on the road.

 

DId a highway run of 160km in the morning with a tail wind 4.1 l/100km. Temperture of -5
On the way home driving into the wind 5.7 l/100km
Temperture of -1C
I buy my pick up would be about 25 l/100km into the wind

 

Indy let me know when your passing through Chicago and I'll install the grill blocking for you. And we can take my grill blocked/ScanGage equipped Prius out on the highway and you can see the temps for yourself.

Wayne

 

Maybe Toyota will read this thread and add computer-controlled louvers over the radiator in a "winter package" for the Prius sold in cold climates.

Earlier in this thread someone complained that heat blocking was expensive and wouldn't justify the cost. Looks like you can use some inexpensive foam from Home Depot http://priuschat.com/forums/gen-ii-prius-modifications/38645-my-attempt-grill-blocking.html
(heck, you could use newspaper and duct tape )

For those of you experiencing lower mpg after a heavy snow during highway driving, perhaps it is the four feet of snow on top of your car that is negating the aerodynamic benefits of the GenIII Prius.
http://www.weirdomatic.com/wp-content/pictures/2007/01/some-snow-on-top-of-my-car.jpg

 

CR-V vs Prius> I've driven my parent's 06, and I can't see that the CR-V is all that spectacular. They have the stick version, which has no arm rest/console. It's just not comfortable on long trips with that omission. And the thing turns far too many RPMs at highway speed. Even at 60-65, it just didn't want to return much better than high 20s to low 30s MPG. But, that's just the way Honda gears their sticks anymore.

 

Just had my lowest MPG trip yesterday. Drove home from work, 30 miles, 18 degrees when I left work, 400+ ft elevation change (uphill), strong head/cross winds (20-25 MPH), first 4 miles were 40 MPH city streets with traffic lights, last 26 miles were 70 MPH on the freeway with CC and I ended up with 39.3 MPG. Ouch! Tank is 3/4 gone and I'm still around 48-49 for the tank though. SG showed water temp around 190 whole time on freeway, bottom grill blocked 100%, top 0%. Still better overall than anything out there!

 

for those who are thinking about blocking their grill. just finished a 28 day experiment with the following results.

points to ponder

1) with limited database, a HUGE variability that results over 40+ driving trips with 40 different driving conditions, etc. this is a very general point only.

2) driving conditions are a total 6.5 mile commute which involves leaving a residential community to go to another less than 3 blocks away, drop off son all at 25 mph and then continue to work in very heavy traffic at 35-40 mph (speed limit which is only obtainable during the first 50% of the commute)

3) first set of numbers was first full tank after winter formula switchover. the weather ran from the mid 60's in the afternoon to a few hits into the high 20's in the morning with average temps in the high 40's. ZERO GRILL BLOCKING

4) temps for the most part, only slightly colder except for the last 6 days when we had temps hit single digits 3 days in a row. before that, we were near 50 mpg... 100% GRILL BLOCKING
[date] [miles] [mfd mpg] [cal gal] [cost] [gal pump] [cal mpg] [$/g]

[11/12/09] [376.6] [40.8] [9.23] [27] [9.856] [38.21] [2.739]
[12/10/09] [485.2] [45.5] [10.66] [23.50] [10.23] [47.42] [2.719]


**disclaimers** this is only one tank but the numbers are simply alarming!. also, if not for the very cold (for us) weather we have had, it would have been 50 mpg which is something that my 2010 cant even do.

the type of driving obviously plays a huge part and with longer trips at higher speeds the difference would be no where near this much.

**edit**

this is for 2006 which has the bladder. so keep in mind, the first tank was under the MFD display, the 2nd is over so that also adds to the error

 

Dave,
Thank you for the nice data.

I think the Gen2 MFD mpg is the more consistent than the bladder tank mpg, and it has only 2% error.
Anyway, I reformat your data using table tag.

	date	miles	mfd mpg	cal gal	cost	gal pump	cal mpg	$/g
1	11/12/09	376.6	40.8	9.23	27	9.856	38.21	2.739
2	12/10/09	485.2	45.5	10.66	23.50	10.23	47.42	2.719

Ken@Japan

 

thank you very much ken. i struggle to post excel (well actually open office Calc... but same thing and FREE!!) info here. how did you do it?