The HR4000 is an electric multiple unit rapid transit car being manufactured by CRRC and assembled in Springfield, Massachusetts for the Los Angeles Metro Rail's B and D lines.

[10] CRRC was awarded the contract as they had the lowest price, the "highest technically rated proposal" and a U.S. content of 65%.

The contract also contained options for 218 additional cars at a total cost of $647 million.

To accommodate the order for additional subway cars, yard expansion work started in 2019.

[15][16] Construction was delayed due to supply chain issues as a result of the COVID-19 pandemic, as well as compliance with the Uyghur Forced Labor Prevention Act.

Internally, it features more longitudinal seating than its predecessors to increase capacity[18] (although early renders depicted against such),[10] as well as open gangways between cars, which come in married pairs.