In engineering terminology, a car jack would be described as a complex machine, rather than a simple one. This is because it consists of multiple, or in this case two, simple machines. These are the screw and the lever.
Although sometimes classed a simple machine, the car jack essentially consists of two other simple machines: the inclined plane and the wedge. The wedge is the pointed tip and the inclined plane is the screw thread, which allows it to be screwed into things.
The lever is defined as either a bar or board that pivots on a fulcrum, or fixed support. This is what raises and lowers the car jack when force is applied.