Question Author
Ethel,
I don`t want to be argumentative, but having read step 4 of the link, I`m still not convinced.
The alternator on my car doesn`t `sense` nor is it computerised and programmed, it`s driven by a constantly turning belt. That produces electricity whether you push the accelerator lightly or not and is returned to the battery. Any excess, as I understand it, when the battery is `topped up` is returned to Earth. In other words going to waste. Therefore why should it decrease MPG to turn the lights on, which are powered by the battery? The alternator doesn`t `know` whether the lights are on or off.