Nice trip report.  Wish my van ran as well.  ;-)

> cruising along at a blistering 58mph according to my GPS (though the
> speedo was happily lying to me saying 63.. ha!). I honestly don't know

I had the same problem with my speedometer being off from the GPS.
When I took apart my speedo to fix my tripmeter, I took off the needle
and adjusted it's position.  Now, it's pretty accurate.  I'm not sure
if it is an approved way to recalibrate the speedo, but it was a quick
fix for me.

-- Craig