considerable amount of time after a crash. General Motors said the first fire would have been avoided if GM's protocols for deactivating the battery after the crash had been followed. These protocols had been used by GM since July 2011 but were not shared with the NHTSA until November 2011. In another statement the carmaker stated that they "are working with other vehicle manufacturers, first responders, tow truck operators, and salvage associations with the goal of implementing industrywide protocols." Customer deliveries of the Opel Ampera in Europe were delayed until the NHTSA completed its investigation of the Volt's battery fire risk to make sure the vehicle is safe. However, deliveries of the first Chevrolet Volts in Europe began in France in November 2011. Deliveries of the Vauxhall Ampera in the UK continued as scheduled for May 2012. Opel Ampera deliveries began in February 2012. Battery enhancements On January 5, 2012, General Motors announced that it would offer a customer-satisfaction program to provide modifications to the Chevrolet Volt to reduce the chance that the battery pack could catch fire days or weeks after a severe accident. The carmaker described the modifications as voluntary enhancements and stated that neither the car nor the battery was being recalled. General Motors determined the June fire was the result of a minor intrusion from a portion of the vehicle into a side section of the battery pack. This intrusion resulted in a small coolant leak inside the battery of approximately . When the vehicle was put through a slow roll, where it was rotated at 90-degree increments, holding in each position for about five minutes, an additional of coolant leaked. With the vehicle in the 180 degrees position (upside down), the coolant came in contact with the printed circuit board electronics at the top of the battery pack and later crystallized. Three weeks later this condition, in combination with a charged battery, led to a short circuit that resulted in the post-crash fire. General Motors explained the modifications will enhance the vehicle structure that surround the battery and the battery coolant system to improve battery protection after a severe crash. The safety enhancements consist of strengthening an existing portion of the Volt's vehicle safety structure to further protect the battery pack in a severe side collision; add a sensor in the reservoir of the battery coolant system to monitor coolant levels; and add a tamper-resistant