The Austrian capital's public transit authority
said it had taken action after a report of the incident appeared
in a Jewish paper.
The 35-year-old driver reportedly said to
passengers: "Can't you
take a joke?" He has since apologized.
The German phrase means "Hail Victory" and was
at mass Nazi rallies in the 1930s.
The driver was running a city center route on
Saturday night when
he bid travelers good night with the words over his public address
The driver did not deny using the words.
Facing felony charge
Media reports said passengers had booed but that
his explanation that it was meant as a joke.
Germany's Der Spiegel quoted the transit authority as saying
the actions were "unspeakable".
A mobile phone video of the incident had been posted
site YouTube but has since been withdrawn.
A spokesman for the public prosecutors' office,
told AFP news agency the driver could face prosecution.
If guilty, he could be given a jail sentence of up to 10 years.
Austria was annexed by
Germany in 1938 and the use of Nazi
symbols is now a crime.