The Tesla Nav maps seem fine as far as accuracy goes. However, I've found that every map system out there has issues somewhere, so I don't doubt that there are places where Tesla's Nav system isn't correct. However, I've driven DFW to Seattle, DFW to Thunder Bay, DFW to Lincoln, and various other places with no issues. Using the cellphone map while driving seems a bit unsafe to me--kind of like texting while driving.
I agree, if the cell phone is not properly mounted directed at the driver to see without moving eyes completely off road. In California, I was watching an experienced traffic commissioner in Santa Clara County explain that a dash-mounted device (made part of the car for the sake of the journey) that is not in itself distracting, i.e., is meant for while-driving use, can, with proper mounting and attention, be a legal means to operate one's nav and audio systems (e.g., an iPhone in a phone holder mounted to the dash properly). I did this in my ICE, and I'm about to do this in my Tesla. A good quality phone mount is mandatory; cheap mounts will fly at you during abrupt driving conditions (any mountain road or sudden stop or turn), and you might get distracted as your $1,000 phone goes flying at your head and other hard objects. A quality phone mount properly tested and properly mounted will prevent this. Unfortunately, the best ones I can find wear out in months, and I just have to get another one; it's a safety concern, so I don't complain, AND the one time I tried to put off getting a good replacement, the phone screen cracked (the worn out mount flew off during a normal acceleration event hitting the car interior and shattering the phone screen), costing me over $150; a quality mount for $40 is clearly cheaper than that, plus anything is cheaper than having an accident. I try out top-rated varieties, and usually find some that work OK.
When that is my situation, I can turn Waze on, try to direct the A/C vent toward the phone in use if A/C is on (and away from phone if heater on) (to keep phone cool since using Waze roasts batteries if the phone is also plugged in, and depletes batteries if the phone isn't plugged in, especially if you also have BlueTooth with Music or Podcasts running too). When this is all true, I then can see the phone basically as safely and easily as any Tesla driver could see the main nav map display on their large screen. I would still use due care and caution only to look when it is safe to look and only to look briefly, even if that means having to accumulate a number of looks at it over time sliced time when traffic conditions don't allow a more sustained look. If I need to see something in particular and can't safely look while driving, I don't look, and take the time and due care and caution to find a safe place to completely pull off the road (such as an offramp with a parking lot nearby), and take a good long look at whatever. This can also double as a break period. I think I will make certain that I also do activities like this during any SuperCharger stops to prevent mid-leg abrupt needs to find random parking like this, but it happens all the time so I'm always ready to take an exit and park to look at my devices.
Using this method in an older car that had satellite-only (no Internet) nav, I would usually start up anywhere between 2 and 4 nav systems: builtin car nav (has a good interface in Mercedes, and I hope in Tesla too -- always worked OK during test drives), Waze, Google Maps, and the iPhone TomTom app, which is ungodly expensive and getting worse, but can work without any network connection at all via storing an entire country or continent in many gigabytes of phone space (so replaces a TomTom device). Since I sometimes mount two phones on the dash, I am able to leave two different apps running side by side. It is rare that I use Apple's builtin map software, but sometimes it gets running by itself when I press on an address, and it's not far enough to get bugged about it, so I let it do its thing rather than fumble with re-entering the address on another app.
I echo what other people have said about using more nav apps for less familiar areas. Generally, I try to remember how to drive without any nav at all, so I intentionally do not start up nav for reasonably short and medium length trips which aren't prone to detours or traffic choices. Other times, I might start just one app, so I have an idea of where backups are; sometimes, Google Maps has the best interface for that. Believe it or not, despite Google Waze and Google Maps sharing ownership and data, they are not equivalent, and running one of each on each of my phones is often the best combination when more than one app is a good idea. (Also, each of my phones has a different service provider -- T-Mobile and Verizon. When I get my Tesla this Friday, that will mean I'll have 3: AT&T is on the Tesla from what I understand. Verizon used to have best coverage, but there are a very few areas AT&T has the better coverage (mostly around hwy 4 in north California), and starting in 2016 T-Mobile has even more good areas that are not good in Verizon thanks to a new band T-Mobile has been rolling out, but only newer pricey phones have had that band.) The more detriments I sense in my upcoming drive, the more nav systems I start and use. I am old enough that I have to pull over just to do this, otherwise I just can't drive properly and set those up. It doesn't make sense to start up 5 nav systems for shorter well known drives in good conditions, but for any drive that has problems such as long, unknown roads, detours, accidents, bad weather, commutes, etc., the more apps it makes sense to start up. Since apps heat up the phones, this is best done in summer with the vent-mount phone mounts with the A/C on and pointed at the phones with the phones plugged in and charging. During winter with the heater on, it is more important to try to memorize good routes and turn the phones' screens off and the nav apps turned off and not running, otherwise the phones could overheat; pulling over, occasionally checking the Google Maps and maybe Waze, then deleting the running processes and turning off the phone screens, tends to be best. Sometimes this will get you stuck in a winter accident, though. I hope the Tesla nav can help plug those holes, so I'll look forward to the car's builtin nav, despite everyone's complaints. Perhaps some vents could be turned off in winter enough to let smartphones cool off. Or a dash mounted fan could be installed that bounces cool window air into the phones.
I look forward to trying the alternative web sites on the Tesla web access. I know I will be using EVTripPlanner.Com, and have already donated. I suspect I will have it bookmarked on my Tesla screen web access. I'm also signed up for all the Tesla smartphone apps I could find, so hopefully any features they come out with will help me, if they ever implement route planning (and I can skip the multiple steps of battery level check and EVTripPlanner.Com, with cross-referencing destination chargers and other sundry trip stops). Someday I hope Waze users can input SuperCharger activity, maybe sharing data with TeslaFi and other apps.
