According to my TCH tank mileage display, my mpg has dropped from a rock-solid 38 since May to about 30 for over a week now.

I've added tire pressure to compensate for temp loss.
I've also read about oil companies changing their blend for the season.

I've always used Shell's 87 octane -- would moving up to 89 help?

I suspect that this is also the result of reduced driving.
My daily commute is less than 10 miles in town.
Is the outside temp sensor running the ICE to keep me warm?

Here's a link to an online article that seems to verify that a Toyota heat recovery system AND an electric-only mode is possible:
http://www.treehugger.com/files/2006...id_minivan.php


Any replies will be appreciated.