25 YEARS No freight car more than 25 years old may be used for interchange service on the U.S. and Canadian railroads. Here's a bibliography of inter alia the rules for interchange service and these people handle specific questions for shippers and carriers. The fastest a freight car goes is usually 70 mph (110 km/h) and the coldest temperatures they encounter are no worse than -50 (Celsius or Fahrenheit, either way much warmer than the upper atmosphere.)