Robert De Niro’s Taxi Licence

I wonder did John Cusack actually drive a limo for a few months for 2012? I wonder did Woody Harrelson actually don a cowboy hat and take on horde's of the undead for a few months? And I wonder did Harrison Ford actually work as a hyper drive mechanic for a while? Probably not! Anyway, one of the kings of method acting was a Taxi Driver for a while, in preparing for Taxi Driver.