The future of the internal combustion engine (ICE) depends essentially on the ability to adapt enough with sustainable products. This means to minimize its impact on the environment regarding gaseous pollutants and particulates. Even more, a significant reduction of CO2 emission e.g., by a possible use of electrified powertrains and, in addition, the ability to run with CO2 free fuels are needed. The first aspect regarding tailpipe emissions must be treated not only considering purely the technical feasibility, but also considering the add on system costs necessary to reach the lowest emission limits. It has been shown in a previous work, that the use of an Electrically Heated Catalyst or Electrically Heated Disk can help to reach a more efficient Exhaust After-Treatment System. PHEV vehicles represent one of the solutions to reduce CO2 and are also enabling some of the obstacles for usage of an electrical heated catalyst. PHEV vehicles have a unique challenge regarding cold start emissions due to sudden torque demands when the electrical propulsion suddenly needs power support. This study focuses on the challenge and discusses PHEVs unique possibilities to pre-condition the catalytic converter. The objective of this paper is to investigate the system design aspects regarding the possibility of the development of state-of-the-art auxiliary air injection with the Electrically Heated Disk (EHD) to minimize gaseous pollutants emission, in particular during cold start, and to keep the exhaust after treatment cost at a reasonable level. Auxiliary air is used during pre-heating to warm up a certain volume of the catalyst above light off temperature to have almost zero cold start emissions. The duration of the pre-heating is a key parameter both for customer acceptance, considering that the ICE can’t be started, and energy management. To assess the efficiency of a new exhaust after treatment, the coming LEV IV regulation has been chosen, where the new US06 cold test cycle has been investigated. It represents one of the future requests for LEV IV legislation for PHEV vehicles. Vehicle tests has been carried out to collect data and was combined with engine test bench measurements. The engine test bench was used to increase test repeatability and reduce cooling time between consecutive tests. As a result, the reduction of pollutant emissions to a very low level, while keeping the system cost at an acceptable level, will be presented.