= When enough excess power is available the rig is powered on and you mine for free.... In your car!
LAWS OF THERMODYNAMICS = there is no free power!
You will be burning more gas/petrol to power it.
Unless that power is already being generated by your alternator and wasted.
This is a fallacy. A car with it's air conditioning on consumes more fuel than one with it off.
I thought that was because engaging the air conditioning compressor adds a load to the belt system that was not there with the compressor off. Likewise, I thought the alternator was always engaged, to provide system power and keep the battery charged. Perhaps I'm mistaken.
The more power you demand from the alternator the harder the engine works to turn it.
It's like a dynamo on a push bike, the harder you pedal, the more power you generate, and the brighter your lights get.