Caterpillar Inc has received 2004 certification by the United States Environmental Protection Agency (EPA) for the company's fourth on-highway truck and bus engine equipped with the company's breakthrough Advanced Combustion Emissions Reduction Technology (ACERT) technology.

The fourth EPA-certified Caterpillar engine with ACERT technology is the C13 engine, designed for general freight or line-haul truck fleets that carry goods such as home appliances, building materials, and refrigerated foods. Offered in the 335- to 430-horsepower range, the C13 is also heavily used in tanker trucks that serve the oil, petroleum and agricultural industries. The C13 is also used in vocational-class trucks including dump trucks, refuse haulers, and cement mixers.