At 01:29 PM 1/22/2009, dhanson@gorge.net wrote...
>my gas guage is laughable, reading 1/2 tank used in about 50 miles and
>reaching the 1/4 full mark after 100 miles...then going through empty
>into the red during the final 200 miles I allow

You seem to be reading it wrong. It's not linear. The top mark is full.
The next mark (about 1/2 in distance from the left) is 3/4. The next
mark (about 1/4 from L) is 1/2 full, the mark at the top of the red is
1/4, mark at bottom of red is empty. With a ~16 gallon tank, and 15
mpg, that's every 60 miles, about. But it's still a rough measure - it
can only be calibrated to be correct at full and empty.

http://images.thesamba.com/vw/gallery/pix/323678.jpg

Regarding the Odo - I had a similar problem which ended up being a gear
on one end slipping on the shaft. I finally fixed it by getting some
green locktite in there to fix it to the shaft (careful not to get any
on the bushing the shaft rides in).