A radio detection and ranging (RADAR) sensor system for vehicles, such as autonomous vehicles, includes a first RADAR sensor configured to provide first RADAR data descriptive of an environment of a vehicle having a first antenna configured to output a first RADAR beam having a first azimuthal component over a first angular range and a second RADAR sensor configured to provide second RADAR data descriptive of the environment of the vehicle, the second RADAR sensor having a second antenna configured to output a second RADAR beam having a second azimuthal component that is narrower than the first azimuthal component of the first RADAR beam, wherein the second RADAR sensor is configured to sweep the second RADAR beam over a second angular range closer to a rear of the vehicle than a front of the vehicle to obtain the second RADAR data.