There are two types of animation possible in MTM2.
Bin model animations, where the game morphs a model through a sequence of different shapes. And texture animations, were the game swaps a texture file mapped on a model.
Animated bins are only for track props, but you can apply animated textures to both track and truck models. BigDOGGe made several trucks with texture animations on the engines (to make the pulleys look like they were spinning) and I've made a truck with animated exhaust flame, etc.
Here are two flags that have been animated. The first is a bin animation, the second is a texture animation. Check out the MTMG's model pages at the links below for more examples.
To make a texture animation, you can do that within BinEdit; to make an animated bin, you will also need Oliver Pieper's BinAnimator program.