I seem to recall that the railmotors I travelled on on the Warburton line were closer to "honorary tram" status (or maybe "railbus") in appearance. They were flat-looking things with a sloping nose. Was it this?

http://www.flickr.com/photos/ryanmarshman/5720689937/

cheers
Tony P
(who spent a lot of time in Melbourne in his first 40 years)