A metal tube with a magnetic base filled with dry ice, or some form of environmentally acceptable smoke machine.
Congratulations, to the casual bystander, your automobile is now a steam train. Some twenty-first century observers may be frustrated that they can't raise their top hats as you pass.
As a user, you have the added fun of not *quite* being able to see through the cloud of smoke in front of your windscreen, unless you opt for the "Stevenson's Rocket" version which disperses the smoke at a higher level.
Comes in at least 3 colours and a choice of designs.-- Fishrat, Feb 24 2006 Stanley Dryer Stanley_20Dryer [theircompetitor, Feb 24 2006] Fantastic. Could also be coupled with hubcaps, front and back on each side joined by a long metal pole, like the drive shafts on old trains. Oh, and a massive (faux) iron cow catcher, too.-- calum, Feb 24 2006 I have always wanted a top hat. Of course, I think that three cornered hats and those long coats with all the buttons, knee britches and stockings would look good on me also.-- normzone, Feb 24 2006 random, halfbakery