It was a mixed week for the auto sector in terms of business developments, but share prices leaned toward the negative side for most stocks. Among the positive developments, Tesla Motors, Inc. ( TSLA - Free Report ) announced a new software update to address the range anxiety of Model S owners. Additionally, AutoZone, Inc. ( AZO - Free Report ) increased its share repurchase authorization by $750 million and General Motors Co. ( GM - Free Report ) announced the new generation of V-6 engines.