A vehicle powertrain variable vibration absorber assembly can be equipped in a hybrid electric vehicle (HEV). The vehicle powertrain variable vibration absorber assembly includes a rotary device, a drive-ratio assembly, and a spring. The rotary device, in an example, is a motor-generator unit (MGU). The drive-ratio assembly, in an example, is a planetary gear assembly. The drive-ratio assembly receives rotational drive input from the rotary device, and transmits rotational drive output to a powertrain component. The spring, in an example, is a variable stiffness spring. The spring is connected to the drive-ratio assembly and is connected to a grounded component. During use, the vehicle powertrain variable vibration absorber assembly absorbs different frequencies of vibration brought about by a vehicle engine amid different operating modes. The operating modes can involve cylinder deactivation technologies.