Toolkit used: Protovis
Data set used: Cars04.xls
For HW 2, I did multiple visualizations for the assignment. When the assignment was returned, there was a comment that "we are looking for a single visualization that addressed all questions". Therefore, for HW3 I first tried the parallel co-ordinates approach, but found it not useful in giving specifics. After which, I wanted to do a Tree-map visualization. The Tree-map visualization, became unreadable as the amount of data increased (I have posted this at the link as well).
I finally settled for Sunburst visualization of City MPG for each car. I have tried organizing the data in a hierarchal structure. First cars, are classified by type, then followed by make, followed by AWD or RWD and then the individual model. If you move mouse over a particular vehicle model you should be able to see the car's CITY MPG.
Final visualization: Sunburst Visualization of Car data
Other trials:
1) Treemap visualization of same data
2) Icicle Visualization