The only one I know for sure is that the Cube has to be the washing machine. All those rounded porthole windows, and the reaction of the hamster in it is like which definitely describes the Cube's looks.
From there, if I had to guess, the colored cardboard box is the Element, due to it's longer shape and being multi-colored (like an Element with the raw black plastic parts) and the toaster is the Scion xB, because, well, it's literally just a rectangle with no styling; just smooth all over.
My 2 cents....
But regardless, that commercial is a classic! We need a ROFL emoticon.
The XB drivers always refered to their car as toasters, I assume the XB is the toaster.
The Cube is the Washing Machine, no real reasoning behind it, but the cube is a negative in the style department, and the washing machine has no styling.
Element is the Box, could be biodegradable cardboard