Does anyone know what the best temperature is for the HCHII in terms of fuel economy? Just curious...

Cold and hot extremes seem to put a big penalty on the HCHII... I'm guessing anything in the 60 - 90 degree range would give "ideal" MPG readings. The other factor (in the range above 75 degrees) is your need for A/C.

It's been over 100 here in Austin for the past couple of weeks. I'm getting outstanding mileage. Over 60mpg, in fact. Yes, that's with no a/c. :-) In general, I've found that 70-80 degrees is optimal because it's warm enough that the car can warm up more quickly yet cool enough to not have to run the a/c.

I believe MPG goes up with temp till the temp equals the temp of the engine block, which must be well over 200 degrees F.

The key is NOT using the AC.

I can tolerate up to 94 degrees F before turning on the AC.
Good thing it has never exceeded 94.

Need fewer troops to support.
Drive a hybrid.
Best tank 71.65 MPG.

Before this car I spent two years learning hypermiling on my 2004 HCH1.

That's probably true for the ICE, but not for the IMA. The battery is designed to basically shut down (no charge, no discharge) to protect it at temps over 100 degrees.

Doppler... you're probably just at the threshold where the battery still operates. A degree or two more and you'd experience the problems we had here in CA a month ago (when temps were 107).... no assist... no autostop... POOR mpg!

Good point. At that point I say set the ac to 99 so it doesn't come on as much

Of course you have to be able deal with swiming in your own sweat. But some of us here are that nuts.

My hydroponics experiment

You ever notice how hard it is to lip read cartoon characters?
"Crazy is what the sane call Delta Flyer"

I can't believe you guys are willing to ride in 94 degree heat without A/C. Frankly, if I couldn't run A/C, I might as well not buy a new car. If I can't enjoy the car, what's the point?

I notice most of those who can drive with windows down at 95 degrees live in Cali or AZ, dry climates. From trips for Pheonix with the dry heat you hardly feel uncomfortable with windows down on the road. In FL or even here in CT on a humid day....wow can't stand it even at only 80 degrees, feels like im swimming in air

I'm near Houston where it has been near 100 and always very humid.
I do a highway commute at 7 AM when the sun is just coming up and the temp is 78 to 84, Windows down is perfectly fine with no A/C, so morning milage is near 60 mpg at 58 miles per hour speed (about 1600 on the tach). When I drive back at 6:30 or so, it is still 92 to 94 degrees, so I cool awhile with AC at 74 then up it to 78 (it's just as cool). Mileage is about 54 to 56 under those conditions, so I don't feel bad. At 97 degrees, all bets are off, and I hope to see 48 mpg! Peter

Peter

I beg to disagree (or maybe I am a wimp). I am in AZ and I get terrible milage when it is over 110 but I refuse to "swim in my own sweat". It may be a dry heat but when it hurts to breathe in the air, that is no fun and it is very uncomfortable.