The automotive industry has been experiencing a rapid increase in the use of reinforced and lubricated thermoplastic composites in high performance, under-the-hood applications.The automotive engineer is specifying plastic composites for weight and cost savings in applications that used to be the sole domain of metals. Long fiber reinforced thermoplastics are replacing die cast metal parts such as fuel rails and fuel cages. Carbon fiber reinforced compounds offer a unique combination of strength to weight ratio and electrostatic dissipation. PTFE lubricated compounds help solve many wear and frictional problems.This paper presents a comprehensive study of the chemical resistance of glass fiber reinforced, long glass fiber reinforced, carbon fiber reinforced and PTFE lubricated composites based on Polybutylene terephthalate (PBT), nylon 6/6, polyphenylene sulfide (PPS), polyethersulfone (PES) and polyetherimide (PEI). The automotive fluids studied are unleaded gas, unleaded gas/alcohol blends, ethylene glycol/water, engine oil, transmission fluid, brake fluid, and Fuel C. The Thermoplastic Composites were evaluated from room temperature to 300°F in a strained (0.25%) and unstrained state.The superior performance of long fiber reinforced thermoplastics when compared to conventional fiber reinforced materials is clearly demonstrated. Among the high temperature amorphous base polymers polyethersulfone yielded excellent chemical resistance to unleaded gas and unleaded gas/alcohol blends.