The cooling system is not complicated but does attract additional demands put on it from the exhaust treatment, which is complicated. My contact with a global engine manufacturer says the bIggest problem moving forward is not emissions compliance its the dressed engine size due to exhaust after treatment equipment. As we know a bigger engine bay leaves less counterweight. Not a problem on larger trucks where the shape can be changed without affecting the operational footprint but "compact" trucks are likely to be bigger than their direct predecessors.