Heater controls set to "Cold" = much faster warm-up

[RobertSmalls]

For two reasons.

Reduced thermal mass: when you set the dial to "cold", it no longer circulates coolant through the heater core and heater hoses. It makes a large difference. I let the car get to 195°F, then turned the dial to "hot", and the coolant temperature dropped 15°F within fifteen seconds due to the mixing of hot and cold coolant.

Less heat gets into the cabin: Even with the fan turned off, air is blown across the heater core and into the cabin. If the heater core is hotter than ambient, the motor loses heat.

An Insight's engine can warm up in a few minutes, so why turn on the heater before then?

[Cobb]

The i2 has a cold engine light and I wait til it goes off before using the heat. I find use of the heat disabled what little EV mode is used and auto stop.

[nayrhyno]

So i have been keeping the heater set to 60 for my cold starts and I have been getting a MUCH faster warm up time. My usual drive puts me on a 55 MPH highway within the first mile, so at that speed the coolant seems to warm much faster without circulating. I hit 6 bars a good 2-3 miles sooner with the climate control set to 60 ECON A/C OFF than when it was set to 65. Once I hit 6 bars on temp guage, i pop it up to 65 or whatever and warm up quick. Its chilly a little longer, but my gas mileage has gone up a bit from it b/c I can get cabin temp up faster in the end.

All told, thanks for this suggestion. Simple and effective.