I've been looking at the Tiger data and the precision. With mcomb's GPS log, I've been able to determine that the accuracy compared to coordinates given by GPS is anything between 0 to 40m.

I'll attach a rather big GIF file which contains a piece of map generated from the Tiger data combined with mcomb's GPS log. The green lines represent the roads and the red line represents the output of the GPS receiver.

To give you idea of the map scale, one pixel represents about four meters.

Kim