DETROIT: General Motors Co said on Tuesday it will invest US$5 billion over the next several years to develop with its Chinese partner a new family of Chevrolet vehicles aimed at fast-growing emerging markets, in the process offering investors a fresh rationale for rejecting a merger with Fiat Chrysler Automobiles NV . For the first time, GM will develop the foundation of a new, global family of vehicles in collaboration with Shanghai Automotive Industry Corp, the state-owned Chinese automaker that is GM's primary partner in China, the world's largest car market.