These are vehicles generated for Fisher-Price Brands and Jim Henson Studios for the feature film;  The Adventures of Elmo in Grouchland. 
At the time, FP Brands held the Sesame Street / Muppets license.  While in pre-production Henson Studios called on product development at Fisher-Price to come up with concepts for background vehicles for the film.

The parameters for this assignment were pretty straightforward; Come up with a handful of vehicles comprised entirely of junk.  The resulting concept sketches were a series of drivable ready-mades that could pass as cars, trucks, and vans for incidental use in populating the world of Junk.

The last 2 vehicles had already been designed for use in the movie, but Fisher-Price and Henson wanted concept drawings for each.
These were already being considered for toys in the line, and they wanted something for context in relation to the vehicles I came up with.