What is your city vs. hwy mileage ?

[jamesqf]

Originally Posted by TestDrive

...it would usually take anywhere from 50 - 100 miles for transmission temperature to stabilize at a peak reading.

Sure - but I bet those transmissions weighed about as much as the whole Insight does :-) And were mostly iron & steel. Aluminium has 4-5 times the thermal conductivity.

[basjoos]

Originally Posted by TestDrive

Wow! That's way more than I'd have guessed. How do/did you determine?

By driving the same scheduled route with or without my lights on under the same temps and wind situation, something that happens regularly when the day length is rapidly changing near the equinoxes. When you are running at the minimal energy budget needed to achieve 70mpg, the power hit needed to run the lights takes a bigger chunk out of that energy budget than it does when you running at an energy splurging 20mpg. On my F150 I can hardly notice a difference between lights on and lights off.

[TestDrive]

Originally Posted by basjoos

When you are running at the minimal energy budget needed to achieve 70mpg, the power hit needed to run the lights takes a bigger chunk out of that energy budget than it does when you running at an energy splurging 20mpg.

Yet another reason to think of FE in terms of fuel unit / distance instead of distance / fuel unit (mpg).
An additional 0.42 - 0.64 gallons consumed per 1000 miles due to lights on.

[wagonman76]

When you're getting the kind of high FE that Bassjoos does, little things like lights do make a bigger cut in FE. I notice zero difference in FE with lights on or off as well. But I do notice with the 6000 wagon, climbing this one hill on the way home from work loses me 1-1.5 mpg. The same hill with the Celeb loses me 2-2.5 mpg.

[TestDrive]

Originally Posted by jamesqf

Sure - but I bet those transmissions weighed about as much as the whole Insight does :-) And were mostly iron & steel. Aluminium has 4-5 times the thermal conductivity.

It's the only vehicle I've ever operated that had a transmission temperature gauge.
Yeah, it's about like comparing grapes to watermelons.
No matter.

Itty-bitty car vs 20 ton 6x6 truck with Allison MT553 5sp AT (and DT466 in-line 6 diesel )

• Greater thermal conductivity >> greater heat dissipation during warm up
  >> longer warm up for oil in itty-bitty car transmission.
• Itty-bitty transmission mass vs MT553's mass (900lbs-1100lbs ?????)
  >> shorter warm up for oil in itty-bitty trany.
• Less work moving 1,500-3,500lb curb weight vs ~40,000lbs curb weight >> a whole lot less friction
  >> longer warm up for oil in itty-bitty trany.
• Tiny or non-existent transmission cooler vs large transmission cooler
  >> shorter warm up for oil in itty-bitty trany.