My RXes heating blower will not come on automatically until the engine coolant temperature rises to 130F, and that generally happens within a mile, ~1/17th of a gallon of fuel (20.59 cents), of leaving the attached non-heated garage.

So what would it cost to bring the engine block up to 130F using a block heater vs not...??

And how much of that 20.59 cents went toward simply moving the RX for that distance vs heating the block and thereby the engine coolant??

Maybe 10%, 2.059 cents...?

Hmmm..

No, wait...

The engine block is CONTINUOUSLY heated, to ~200F yet.

So, until the coolant heat rises to the point wherein the EXCESS is dumped overboard isn't that HEAT free of cost...??

It seems to me that the only time there is "value" in the engine coolant heat is for cabin heat, otherwise ALL of it is THROWN overboard.

That can't be right...or can it...??

That would mean that the cost savings for pre-heating the engine blocking would be ZILCH,...or maybe even NEGATIVE.

And then there is the catalyst, that MUST be heated to something like 800F before becoming fully operational. Does pre-heating the engine block allow more of the "initial" excess heat derived from "fuel burn" to flow into the exhaust and thereby help to heat the catalyst sooner?

Wow, too many variables for me, 'way too many.

A cold-start is the most fuel inefficient period of operation, under 20 mpg and at times under 10 mpg. The value of an EBH wrt FE is to allow ICE to cycle through the five warm-up stages of hybrid operation sooner. During the 1st stage, the ICE always runs as long as coolant is below 104F. Use of EBH cuts this high fuel usage period by 2-3 min. The goal is then to reach stage 4 (full hybrid mode) and stay there, as soon as possible. HiHy has an 80C/182 F thermostat and takes about 35 min to reach a stable 185 F. ICE will restart at low speeds when coolant temp drops below 73C (163.4 F), which happens frequently below 32F.

During my morning drives, without EBH, ambient temps 30-40F, and a radiator screen to retain heat, the ICE is off 30 - 33% of the time (35 mpg). With a 3 hr EBH cycle, ICE is off 45 - 50% of the time (43 mpg).

"about 35 min to reach..."

Typo...??

Did you mean 3.5 min...??

But what about stage 2 of the "warmup" stages, the ice will remain running even with the (pre-heated) coolant up to 182F until the catalyst is at ~800F.

No typo. See below.

Time Period------Avg Coolant (F)
Zero - 4:59 ||150.8
5:00 - 9:59 ||178.9
10:00 - 14:59||179.8
15:00 - 19:59||180.8
20:00 - 24:59||181.0
25:00 - 29:59||178.5
30:00 - 34:59||183.3
35:00 - 36:45||185.2


Steady state coolant temp is typically not reached until the 35 min point in my drive.

Remember, ICE is not running continuously after S1. When in S2, ICE shuts off only when not needed (@ 0 miles per hour) or in neutral. During my morning commute, ICE is off only 5 - 6% of the time when in S1/S2.

In S3a/b and S4, ICE can enter stealth mode (< 42 miles per hour). For my drive, ICE is off 63% of the time once I'm out of S2. I have a lot of rolling hills during the middle part of my commute, so when running, ICE recharges battery on upgrades.

What's important about your table, at least for me, is the coolant has reached 90% of the "target" within 5 minutes.