That's the rear wiper fluid reservoir. Holds the wiper fluid for the
rear wiper.

On Dec 8, 2005, at 11:08 AM, Michael Diehr wrote:

> - had a mysterious black plastic bulge on the right interior wall
> about 2 feet forward of the hatch.
>   what is this?  The owner said he opened it once and it looked like
> a filler cap.
> - had an even more god-awful color scheme.  My 85 is just brown and
> tan.   This 84 was orange
>   with an interior that was tan & brown with brown & striped blue
> pinstripe fabric.