Alternator linked to mileage?

[the_same_mountainbike]

I have a link to the knowledge “piece” that you’re missing: http://science.howstuffworks.com/electricity2.htm

Remember that a generator (a car alternator is a generator with a “rectifier” to turn the AC into DC) functions by dragging windings through magnetic fields. The more current is being drawn through the windings is the stronger the magnetif field and the more force that will be required to drag the fields from the armature windings through the stator fields.

Remember also that 100% of all the energy use dby your car, including that used by the lights, originates in the gasoline. It’s turned into electrical and mechanical energy through the car’s various systems.

Short version: lights need energy, that energy comes from the combustion of gasoline. More lights need more gasoline.

However, the affect on your mileage of DRLs being lit is extremely minimal. The cost of the accidents you’re probably preventing is extremely high. I recommend strongly against turning the DRLs off.

[B.L.E]

A radio using the same power at all volume levels is true if you are talking about a 5 tube AM radio with class A final amplification.
Modern transister amps today almost always are class B push-pull outputs which not only are more efficient than class A amps but also use very little power when the volume is low.
The “rheostat” that attenuates the volume is in the circuit before the final amplification.