Sorry I doubted you on affect of heat on MPG

I find that holding my breath helps in winter as the windshield doesn't fog up as much so I can keep the heater off.

 

Tony,

Very informative info display. Thanks.

Can you offer any thoughts on why your FE/MPG's took the slide in 2009?
It doesn't look to be temps related.

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We're 10% ethanol all year round here and winter mileage will suck.

While the winter swing for the Prius isn't as great as mpg makes it seem, the Prius is affected more because the EV system is affected by temperature.

It'd be interesting to see a mileage curve for a regular car. You should see a similar but gentler curve.

 

Maybe it rained more.

 

What a load of hyperbolics!

Don't suppose you have it or can produce it in gp100m? That should show the variation more realistically.

 

Snow tires. With the Prius, as with any other car, good snows tires will make all the difference especially given the poor performance of the stock tires in the wet.

 

I am playing with reasons it can get 'too hot'.



The sending unit for outside air and for intake tract air are not calibrated, so may vary even if the air temp is really the same.

1) the engine compartment may not be able to 'clear' the hot air generated. (I have no grill block yet)
2) the aluminum intake runners may be being heated by the hot cylinder head
http://www.outlawengineering.com/tech.html
3) more intake air may be allowed back up into the runners
4) the anti throttle plate freeze protection may be excessively effective

 

Here's a thread on this from a while back, '07.
It would appear that on the Prius there is very little throttle plate heating
required.

http://priuschat.com/forums/gen-ii-prius-modifications/39277-no-hot-water-bypass-car.html

 

My max mileage occurs when the average outdoor temp is about 75-80. That's the daily average so that means it's about 65 at night and 90 during the day. It's warm enough to warm up the engine quickly but not too hot where the AC is on.

Tony lives in a cooler climate and his mileage is max at his local peak temperature - but that is well below the peak we see here.

 

But how do you feel about it?

Grammar Girl : Affect vs. Effect

Sorry, the psychologist in me just could not resist.

 

^^ lol.

Mike, I would not read too much into mpg readings from a day or three. There are too many confounding variables. Wind, e.g. So while it is true in general that Prius mpg starts to decline as temps drop below 70F or so, the slope is very moderate until you hit under 40F unless the trip is short.

 

IMO 1 mpg increase within a single tank in non-controlled conditions is statistically irrelevant. I vary several MPG from tank to tank seemingly while doing the same thing. It's just impossible to conclude anything from one MPG in the scenario outlined in first post.