Docklands: Head down past New Quay on Docklands Drv .. where the tram line runs now .. all the way down to the end, it turns to dirt .. turn left abit and you'll be right under the bolte bridge.. it looks awesome at night!
Theres also, North Wharf Rd.. Head to the very end where the wharf ends and you can get different shots of the car and bolte bridge.. Probably a better location (if you can still get down there).
Yarra Bend: Cannot remember the actual road name .. I think its Yarra Blvd, Turn right off Johnston St (Fitzroy/Abbotsford) onto Yarra Blvd .. Nice little drive it is too, awesome sweeping corners, tightening hair pins.. Anyway, towards the end there at the top of the last hill, theres a corner with some parking to the left of the road and theres a great backround of the whole city.. Good for day or night.
Sky high: Top of Mt Dandenong, tourist lookout.. Follow canterbury rd to the top of the mountain.. get to 5ways and go right then left.. follow til you see signs for the tourist lookout.
Williamstown: Not east .. but not far from the city, along the waterfront of both ocean and back towards the city..
I just re-read your post and I hope your refering to photo spots for cars, it doesnt actually say.. otherwise this post is pointless.
Good luck with it .. and please post some shots when your done!

Edit: I'll try and think of some more, but having not lived there for a year and a half .. its kinda hard..