Sorry I doubted you on affect of heat on MPG

I am not sure how many digits after the decimal point the US model has but remember that 51.5 would show 52 and 51.4 would show 51 if there is no digit after the decimal point.
Nothing you can do against the rounding effect.

 

Yep, 62 mpg for the last gallon.

I waited until I had a scangauge before blocking my upper grill (G2 Prius) out of fear of overheating. I didn't even get close, in fact the radiator did not come on the entire winter. That said, if I lived in coastal Cali where 'cold' is 50F, I would not block either.

 

It's that time of year again. Air temps start to creep down, and we'll be
seeing a quite few first-time summertime buyers seeing slowly
dropping MPGs and wondering if their car is broken. It happens every
year.

There are members with Gen IIs who block one or both grills all the time.
I'm one of the ones who has ScanGauge and keeps the upper grill
blocked the year 'round.

We've seen atypical late summer daytime temps in the high 80s-low
90s, so I've held off putting the lower grill blocks in. I put the four foam
pipe insolation strips in one at a time: At 70 degF daytime temps the
first one goes in at the top. At each 10 degF drop, another goes in.

I've also added some insulation to the engine itself, which seems to be
a help combating heat loss as well. I'll put it in when temps hit the 50's:

http://priuschat.com/forums/gen-ii-...radiant-heat-reflector-gen-ii.html#post979632

 

Cool?

Try temps well below freezing, for the daytime high.

Sitting in heavy traffic caused by snow & ice provides a very different perspective.
.

 

ok, newb question time. why would the Prius get better mileage in hot/warm weather? I mean we have to run the a/c when it is hot which has to affect the mpg. in cooler weather, in se texas means <80, we won't run the a/c which should increase mpg. our weather is wacked here, we could have 50 for a high one day, 85 the next then 60 the day after that.

my commute to work is about 4-5 miles at a max speed of 45 mph. I would ride my bike but with no shoulder and drivers who don't respect people on bikes it is too dangerous.

 

Up here in the northwest winter is mostly rain 8 days a week. MPG always drop down into the mid 40's.

al

 

The terms cold, cool, warm, and hot have meaning relative only to a
posters particular experience and location. Given the wide geographical
distribution of PRIUSchat members, they can be confusing, even meaningless.

The Prius delivers the best mileage in the same temps we humans like.
In general, the best temps for high mileage are between 50 and 80 degF.
In this range most folks don't need to ask for either heat or cooling. As
a result, with careful, attentive driving most, make that virtually all of
the little gas that is burned goes to moving the car.

High mileage follows. :rockon:

 

Never mind.

 

Here is my years of meticulous data. The car gets the best mileage when the temperature is warm, but not really hot.

 

Nice data! Out of curiosity, what are your A/C habits like?

 

I envision probably not driving the Prius as much in the coldest months. Since buying it in April, it's been the "go-to" car, but that may change.
I'm also concerned about getting caught out in a snow event - something that happened to me in my RWD Volvo last year, due to weather forecast being off, and I don't wish to repeat that adventure in a non-AWD vehicle...

 

On the question of my A/C habits . . .
I live in the Dallas area and it can get pretty hot and sticky. In the summer I'll sometimes drive with the windows down in the morning, but my commute is mostly highway so when I get over about 45mph I usually roll up and switch to A/C to cut down road noise and drag.

I do park in a parking garage during the workday, so my car only needs modest cooling when I commute home. If I had to park in the sun and cool it down it would be worse.

When you see average temperatures in the upper 80's on my chart that means we are near 80 at night and about 100 in the day.

 

i think most of the misconception about temperature and fuel mileage comes from the fuel you get at different times of year.

people tell me heat helps mpg. more like there is no ethanol in your gasoline during the summer, so you'll get more bang per gallon. people also say cold helps mpg, more like you don't run the a/c during the winter, helping reduce fuel usage.

temperature and mpg is a bunch of different factors. i doubt its related. the internal temperature of the engine is the same regardless of outside temperature. touch your engine during the summer, and the winter. you'll burn it both times...lol.