battery below 30%. GM also expected the battery to withstand 5,000 full discharges without losing more than 10% of its charge capacity. According to GM, , no batteries had been changed due to degradation. In April 2008 GM started extensive battery testing. In two years, the carmaker put the battery packs to the equivalent of 150,000 real-world miles (240,000 km) and 10 years of use. The durability of the battery pack was tested for a broad range of extreme ambient conditions including a shaker table to simulate potholes and a thermal chamber, to simulate temperatures varying from , typical of the Southwest deserts, to typical of the Alaskan tundra. In April 2008 the lithium-ion battery pack was placed in Chevrolet Malibus fitted with the Volt powertrain to be used as test mules for further real-world testing. In October 2008, GM chose CPI (LG Chemical) to provide the battery systems for the first production version of the Volt. In July 2008, GM confirmed that a non-turbocharged, 1.4 L 4-cylinder engine would be used as the range extender, and that the intention was to build it in Flint, Michigan. In April 2009, General Motors let journalists test the Volt powertrain without the range-extending generator in the body of Chevrolet Cruze sedans that GM used as test mules at the GM Technical Center in Warren, Michigan. The first pre-production test car based on the final Volt design was built in June 2009, in Warren, Michigan, and by October 2009, 80 Volts had been built and were tested under various conditions. On March 31, 2010, the first factory-built Volt was produced at the Detroit Hamtramck Assembly Plant to test the production line and for quality control purposes, both of the tooling and the pre-production vehicles produced before regular production began. Tony Posawatz was the Volt Vehicle Line Director from 2006 to 2012, and he was known as employee #1 and led the team from concept to production. Official introduction General Motors held a ceremony at its Detroit Hamtramck Assembly Plant on November 30, 2010, to introduce the first Chevrolet Volt off the assembly line. The first Volt built for retail sale was earmarked for display at GM's Heritage Center museum in Sterling Heights, Michigan. The second unit was offered at a public auction, with an opening bid of and it was won by Rick Hendrick who paid . The proceeds went to fund mathematics