- Cat® wheel loaders set the standard for productivity, fuel efficiency and operator comfort. The Cat 906 Compact Wheel Loader has a high torque C2.8 engine that works in conjunction with an intelligent hystat power train to deliver exceptional fuel efficiency. Dependent on regional requirements our engines meet U.S. EPA Tier 4 Final and EU Stage V emission standards with a clean emission module designed to manage itself so you can concentrate on the task at hand or emit equivalent to U.S. EPA Tier 3 and EU Stage IIIA.