Lupin III: Part 5

Both are crime stories (in a variety of infiltration, heists and spionage jobs) with (mostly) adult cast and lots of comedy and action. VERY similar animation, direction and music. 

TGP is like a cross between Lupin III and the live action show Leverage (which I would also recommend) but it is hard to break into a style that already has been done so well time and time again. Like TGP the smaller stories come together to form an overarching narrative. There are plenty of "that could never happen" moments while utilizing the support of top class writing that balances the comedy, action, and enough drama to keep it interesting in between. 

They both have a very iconic group of 4 people. and the director of Cowboy Bebop openly admits that Lupin inspires the creation of Spike. 

Lupin and Favaro remind me quite a bit of one another. Additionally, you have the strong, young female character in Nina and Ami. Both are lushly animated, with fantastically epic music and storylines that build off of one another, though vastly different settings.