That's an... interesting question!
Unfortunately, it's not possible for a poop to propel a car. Poop is a biological waste product that doesn't have the physical properties or energy density to generate the force and motion needed to move a vehicle.
Cars require a significant amount of energy to move, typically in the form of gasoline, diesel, or electricity, which is converted into mechanical energy through an engine or motor. The energy released from burning fuel or electrical energy is what propels a car forward.
Poop, on the other hand, is a soft, organic material that doesn't have the capacity to generate significant force or energy.