Environmental regulations, energy conservation considerations, and consumer pressures have influenced significant changes in automotive design. Some of these changes have created environments that are particularly detrimental to elastomers. A specific example of this is the automotive underhood environment. Due to “downsizing”, front wheel drive and better aerodynamics, the already harsh environment of fuels, oils and chemicals has been accelerated by increased underhood temperatures. These increased temperatures have pushed many commonly used elastomers to their limit. This paper discusses the attributes of chlorinated polyethylene elastomers and how they fit into the increasingly demanding automotive underhood environment.