Use of ethanol in Chrysler products

Mabee Inused the wrong term.
My definition of thermal efficiency is the number of BTUs of heat
turned into useable HP as a ratio to the amount of BTUs in a pound, or
gallon, of fuel.

One hp is 42.375 btu/minute, or 2542.47 btu/hour.
Diesel fuel has something like .13 or .14 million BTU per US gallon.
That is 130000-140000 PTU per US Gallon. At 100% efficiency, an engine
running on this fuel would produce (140,000/2542.5)= roughly 55 HP for
one hour on one american gallon.

If the engine only produces 27.5 HP for an hour, or 55 hp for 30
minutes on a gallon, it is 50% efficient - and since the only place
the rest of the BTUs go is producing heat and noise, the thermal
efficiency is just SLIGHTLY under 50%

I do not have the BTU content of gasoline right at my fingertips - but
it is lower per gallon - closer on a per lb basis - Gasoline has an SG
of roughly .74, and Diesel about .84, so gasoline is LIKELY about
123,000 BTU per gallon

A gasoline engine converts about 15% of the fuel it burns into power
to move the car, and another small percentage to run power steering,
friction losses in the drivetrain, running AC and charging system,
etc. Overall - something around 23-25% "efficiency"
The base 15% is closer to 24% in a diesel, with the actual "efficiency
pushing 30%

You are talking more of cooling efficiency, I think - and cooling
efficiency increases when operating temperatures increase, because the
"Delta T" between the coolant and the outside air is higher. This is
NOT what I was talking about.