well someone already mentioned chitty chitty bang bang.

i'd argue the 60s (to early 70s?) were the "golden age" of steampunk with all those jules verne movies and victorian era retro films...
20,000 leagues under the sea
chitty chitty bang bang
those mangnificent men in their flying machines
those fantastic flying fools
the assassination bureau
around the world in 80 days
first men in the moon
&
the great race... AWESOME steampunk car!!!

THAT is the baddest steampunk car!!!
no one mentioned league of extraordinary gentlemen car

all i planned on adding was the avatar: legend of kora "hotrod"

and forgot about the police car

here's a good one...
(there's plenty of other great ones if you keyword "steam engine car"

here's another good one...
