Cologne is a city in Germany and is featured in F9.
At some point after the events of The Fast and the Furious: Tokyo Drift, Twinkie secures work for himself, Sean Boswell and Earl in Cologne where they are paid to build rocket engines for the Military. At some point, the trio build a Pontiac Fiero powered by a rocket engine.
After Dom's crew go their separate ways to find information about Otto, Jakob and Han, Tej and Roman go to Cologne, on advice from Dom, to meet with Sean Boswell, Twinkie, and Earl who can provide them with cars, weapons and everything else they're after.
It was there that they learnt that they've been building a Pontiac Fiero rocket car for the Government and Roman and Tej witnessed the first launch of the car when it raced against a jet, however this resulted in the car blowing up and needing to be rebuilt.
Tej and Roman asks for cars and gear and that they were sent by Dom, however Earl asks "who's Dominic Toretto?".
- The scenes for Germany were actually filmed in Scotland.