[link|http://www.motorcycle.com/mo/mcnuts/sparrow.html|http://www.motorcycl...nuts/sparrow.html]
There are a couple of these in use running from the island to Seattle. I see them on the ferry a lot. They have the best of most worlds. They pay motorcycle rates and load/unload with the cycles - which means they go straight to the head of the line everytime, even when car wait lot is maxed to capacity.
OTOH, during the rain, you stay dry.
They're kind of spendy for a single seat though.