In 2006 a company stacked six Mercedes "Smart Cars" about 12 m high in Sydney to promote their carsharing scheme. These schemes are becoming popular for people in the inner city who want occasional use of a car for short periods.
By the way the company doesn't normally park their cars in a stack in squares, they arrange to have reserved parking spots at locations around the city.
I was reminded of this recently, as the company sent me a note to say their web address has changed and on the web site I noticed they were going to do the car stacking stunt again. Has anyone see it in Taylor Square?