Ignoramus6950 wrote:

I was thinking about electric cars today.

An internal combustion car, burns fuel inside cylinders and produces
energy according to Carnot cycle. Say, it makes 28% of energy from the
total BTU of fuel that it burns.

Not even close. A good Otto-cycle engine gets maybe 13% efficiency
at near wide-open throttle. At typical mid-throttle operation, it is
much worse, maybe 5-8%. A semi-Atkinson cycle engine like in my
Honda Civic Hybrid does better at mid-throttle, as does a Diesel by
eliminating pumping losses.

So, a standard gas engine is a lot worse than you might imagine.

Most of the electrical gear is WAY more efficient than that, hence
small heat sinks and minimal cooling system are needed.

No, the losses in the electrical system are small compared to the
incredibly poor efficiency of the typical gas engine. Any time you have the
gas pedal less than floored, you are practically driving with the brakes
on! Read up on "pumping loss" if you don't believe me.

Then, look at the VAST amount of heat going out the tailpipe, and the
significant amount of heat going out the radiator.

Just being able to drive without these massive heat losses gives some idea
of the efficiency of electric vehicles.

Compare the KWH energy loaded into the batteries of a typical EV against
the BTU content of a tank of gas, you won't believe the numbers!

Jon