Book excerpt: This handbook deals with the vast subject of thermal management of engines and vehicles by applying the state of the art research to diesel and natural gas engines. The contributions from global experts focus on management, generation, and retention of heat in after-treatment and exhaust systems for light-off of NOx, PM, and PN catalysts during cold start and city cycles as well as operation at ultralow temperatures. This book will be of great interest to those in academia and industry involved in the design and development of advanced diesel and CNG engines satisfying the current and future emission standards.