Originally Posted by riredale

No, I'm not talking about using an engine block heater. That would certainly be useful if the car is cold-soaked overnight in very cold weather--and if a power cord were nearby.

What I wonder is why the hybrid maker couldn't fabricate a thin block-hugging insulating blanket so that the block would be very slow to cool down once the engine was turned off. Up here in Oregon right now it's perhaps 40 degrees Fahrenheit during the day. Say I drive to get a haircut, the engine almost reaches operating temperature by the time I get there. I come out 30 minutes later and the temperature gauge is back on "C." With insulation it would probably have dropped only one notch or even less, and I'd be getting 30mpg on the drive home. Plus, instant cabin heat.

Yes, adding a blanket would not allow the block to radiate heat, but I have a suspicion that block cooling is only a few percent of the total heat exchange, something the radiator could easily take up.

Anyway, just a thought, but I won't be surprised to see this as standard practice on hybrids (perhaps even non-hybrids, though the gain would be less) five years from now.