In a statement released Monday, GM said the Volt's battery sustained moderate damage, not the destruction that would have been caused if the fire had started there. The same was true of the cordset and charger.
The fire broke out Thursday in an attached garage in Barkhamsted. The garage belongs to Storm Connors, who owned the Volt and a 1987 Suzuki Samurai he had converted to run on electricity.
Both cars were recharging at the time, the Hartford Courant reported.
Smoke was discovered coming from underneath the Volt on Monday morning.
"The rekindle this morning really adds to the mystery," Barkhamsted Fire Marshal Bill Baldwin said.
The Volt was introduced in December and about 1,500 have been sold. The vehicle includes a small gasoline engine for recharging the battery, so it is classified as a hybrid rather than an all-electric car.
Connors could not be reached for comment, the Courant said. He is a volunteer firefighter who lists his occupations as training consultant, clown and magician.