It depends on what you want to achieve!
If it is fuel economy that you are after, then use it only when you have to move the car for a short distance ( so short, that you do not want the ICE to fire, like in parking lots or to clear your driveway).
Traction battery charge is replenished by the ICE and conversion has its price (losses).
The worst is to use it first thing in the morning, ICE is cold and warm-up cycle is best done without adding unnecessary load on it.
If it is fuel economy that you are after, then use it only when you have to move the car for a short distance ( so short, that you do not want the ICE to fire, like in parking lots or to clear your driveway).
Traction battery charge is replenished by the ICE and conversion has its price (losses).
The worst is to use it first thing in the morning, ICE is cold and warm-up cycle is best done without adding unnecessary load on it.
