Systems and methods for improved tracking of articulated vehicles can obtain, through one or more sensor systems onboard a vehicle, sensor data descriptive of an environment of the vehicle, the environment including an articulated vehicle having at least a first portion and a second portion; generate based on the sensor data, first state data for the first portion of the articulated vehicle and second state data for the second portion of the articulated vehicle; determine an articulated vehicle relationship between the first portion and the second portion based on the first state data for the first portion and the second state data for the second portion; generate, using an articulated vehicle motion model, synthetic motion data for the second portion based on the first state data for the first portion; and update the second state data of the second portion based on the synthetic motion data.