Slowrain beat me to Martin Cruz Smith and others as we share similar tastes. Nice job! As mentioned, Philip Kerr's Bernie Gunther series is set in 1930s-50s Germany and a little in South America.
Staying in 1930s-40s Germany, there's also Rebecca Cantrell's series beginning with
A Trace of Smoke; and David Downing's starting with
Silesian Station, which leans more toward espionage/mystery.
For more espionage/mystery, there's Olen Steinhauer's series set in Cold War Central Europe, but I've never read him outside of his recent
The Tourist, which didn't quite do it for me. Slowrain, maybe you have?
In the same vein there's also the underrated master Charles McCarry, whose novels carry you all over the world.
I'll stop there. For now.
Steve