Railroad tank cars are provided that include an inner tank, an outer tank, and tank to tank clearance between the inner tank and the outer tank. Insulation and spacers can be located within the tank to tank clearance. The inner tank can shift within the outer tank, and spacers can crush, under significant force loading, such as impact forces generated during a collision or derailment. The inner tank, insulation, spacers, and outer tank thus form an energy absorbing system that reduces the likelihood that the inner tank will be breached, and that a hazardous material contained therein will be released, under such conditions.