Milwaukee Road class F7
The F7s are major contenders for the fastest steam locomotives ever built, as they ran at over daily. One run in January 1941 recorded by a reporter for "Trains" magazine saw achieved twice—in the midst of a heavy snowstorm. Baron Gérard Vuillet, a French railroading expert, once recorded a run between Chicago and Milwaukee where the locomotive reached and sustained an average for . However, the British locomotive LNER Class A4 4468 "Mallard" is officially accepted to be the world's fastest, with a run recorded at but authenticated at 126 mph in 1938.
LNER Peppercorn Class A1 60163 Tornado
With a shorter rake of eleven coaches compared with the original Peppercorn A1's usage, "Tornado" is expected to achieve contemporary main line speeds. Theoretically capable of , "Tornado" may in the future gain permission to run at , making her the fastest steam locomotive on the British main line. "Tornado" is expected to see main line use until its ten-year fire-tube boiler re-certification in late 2018.