Today was my first road trip. I checked my route on Google maps via the computer before I left: 157 miles.
When I put the destination into the Model S nav system: its route suggested 189 miles!
I ended up driving the route Google provided. It kept trying to suggest a longer route, and I kept ignoring it. At one point, it was so insistent on having me avoid a certain road, that it suggested a route that looped around, just to end up in front of me. In other words, in the driver's console Navigon display, I could see the suggested route veer off to the right, run a big loop, and then end up in front of me--even though it also showed the road I was currently on, which went straight and was several miles shorter. I continued on the "straight route", and it wasn't until the last mile or two that it finally suggested I continue on the road I was on. Didn't make sense at all.
"Navigation by Tesla". I know this will be improved with the big update due out later this summer...I hope the next version of the NAV software is better at route finding!