When the propulsion battery got low the ICE came on to charge the pack. The garage must have been filled with carbon monoxide. Subsequently, Chevrolet has issued a recall but to fix this problem I will have to make an appointment, take time to take the Volt to the dealer, and arrange transportation back and forth. A similar problem with a Tesla and we would have had an over the air update while we were sleeping. That is the tecnological lead that Tesla has over the competition.