We just took a trip from LA to Phoenix. On the way we made two stops at superchargers. Both times the car told me I had enough charge to move on with my trip despite the fact that it projected me having 10% battery charge when I got to my destination, basically no buffer. That wouldn't be so bad were it not for the fact that as soon as I continued on my trip the estimated state of charge on arrival dropped significantly both times. From the first supercharger we went from the car estimating itself to have a 32% charge at the next supercharger to 20% in a matter of 10 minutes. We pulled in with 10%. Then we left that supercharger and it said we'd have 20% charge left when we got to our destination. We pulled in with 4 miles. I get that the EPA ratings are based on a certain speed but the navigation doesn't need to be and if it's basing state of charge on a 55mph assumption then it should give you the option of inputing your speed so it can tell you how long you really need to charge to be able to continue on at your desired speed. I'd rather hang out at the supercharger for another 10 minutes and be able to drive 75mph than rush out and have to drive 55mph to putter into the next station. In either case had I departed the supercharger when the car told me I had enough charge to continue, I would have ended up dead on the side of the road or completing a large portion of the trip at 55mph in the right lane. No bueno.