Tank car design requirements and tank car safety research both evaluate impact conditions for a fluid filled tank. For the test conditions, the fluid is typically water or water based slurry that has an appropriate density to represent a specific lading. The pressure is commonly applied to the tank using compressed air. In analyses, the effects of the fluid are often included using computational simplifications such as adding the weight of the fluid lading to the tank mass and adding a constant internal pressure to the tank. For specific impact scenarios the effects of these modeling approximations have been analyzed to assess the magnitude of the effects on impact and puncture behavior. This paper describes analyses performed to evaluate the effects of the lading on the impact and puncture behavior of tank cars. The lading is explicitly modeled in various impact conditions to assess the behavior of the lading and the effect of modeling approximations on the dynamic response. In addition, the effects of the internal pressure and outage volume of various commodities on the puncture behavior are also analyzed.