Chevrolet Volt electric vehicles have achieved up to 39.9 miles of emission-free

The Volt, which can travel up to 300 miles beyond its pure electric range because of a small on board gasoline engine, recently completed a round of cold weather testing in Kapuskasing, Ontario, Canada, and will undergo additional hot weather testing in Yuma, AZ, in June and July.

The Volt remains on schedule for start of regular production in the fourth quarter. Farah, chief engineer for the Volt and the Opel Ampera, said more than 500,000 test miles have already been put on the pre-production Volt electric vehicles.

Farah said engineers at GM’s Warren, Mich., Technical Center will begin building pre-production versions of the Ampera later this month in preparation for its launch in Europe for the 2012 model year.

Monday’s update followed the announcement that GM plans to invest an additional $8 million to double the size of its automotive battery lab in Warren.

Micky Bly, GM’s executive director of global electrical systems, hybrids, electric vehicles & batteries said more than 300 pre-production packs were slated to be built at GM’s Brownstown, Mich., battery plant.

So far, more than 850,000 miles of customer use lab testing have been completed on the battery pack design for the Volt and Ampera. Bly said the team continues to study additional applications of the Voltec battery-based propulsion system in future vehicles, although no details were provided.