General Motors has announced enhancements to the vehicle structure and battery coolant system in the Chevrolet Volt in response to a National Highway Traffic Safety Administration (NHTSA) preliminary evaluation to examine post-severe crash battery performance.

NHTSA opened a Preliminary Evaluation on November 25, 2011 following a severe-impact lab test on a battery pack that resulted in an electrical fire six days later. The test was conducted to reproduce a coolant leak that occurred in a full-scale vehicle crash test last May that resulted in an electrical fire three weeks later.

The Volt is a Top Safety Pick by the Insurance Institute for Highway Safety and has earned other safety awards from key third-party organizations. Through the first 11 months of 2011, Volt owners accumulated nearly 20 million miles without an incident similar to the results in the NHTSA tests

“The Volt has always been safe to drive. Now, we will go the extra mile to ensure our customers’ peace of mind in the days and weeks following a severe crash,” said Mary Barra, GM senior vice president of global product development.

GM will conduct a Customer Satisfaction Program to further protect the Volt battery from the possibility of an electrical fire occurring days or weeks after a severe side crash.

GM conducted four successful crash tests between December 9 and 21 of Volts with the structural enhancement. The enhancement performed as intended. There was no intrusion into the battery pack and no coolant leakage in any of the tests.

“These enhancements and modifications will address the concerns raised by the severe crash tests,” Barra said. “There are no changes to the Volt battery pack or cell chemistry as a result of these actions. We have tested the Volt’s battery system for more than 285,000 hours, or 25 years, of operation. We’re as confident as ever that the cell design is among the safest on the market.”

Volt customers will be individually notified when the modifications are available for their vehicle. The enhancements are being incorporated into the Volt manufacturing process as production resumes this month.

“We’re focused on one thing right now: doing what’s right for our customers,” said GM North America president Mark Reuss. “We’ll live up to our commitment to make sure our customers are delighted with their purchase.”