Would Have the Greatest Inertia?

Inertia is a definition of mass so an object with greater mass will have greater inertia. The mass of the engines of the airplane on their own probably have more inertia than the car. Mass is usually measured by determining the weight of the object, which is defined as the gravitational force pulling down on it.

What will have the greatest inertia?

Objects with greater mass have a greater inertia; objects with less mass have less inertia.

Which animal would have the greatest inertia?

In a situation where we compare the inertia of a mouse to an elephant, it is easy to see that it is the elephant that has more inertia.