I recently used Tesla’s smart navigation system to drive from Wrocław (Poland) to Berlin (Germany) and back, and then I used it again a few days later on a long trip to the Polish boonies. Tesla doesn’t call it “smart navigation” — just sticking to the boring basic term “navigation” instead — but this beast is brilliant and performed much better than I expected. However, I learned something from these drives that I think anyone using this navigation option should know ahead of time. I’ll get to that in a minute.
After my drives, one of my Tesla Shuttle partners took another long round trip in our Model S 85D (from Łódź to Berlin and back). This trip uncovered another important takeaway for people planning long trips with Tesla’s smart navigation system (or otherwise planning long trips in an electric vehicle), something that could really make the difference between making it to your destination as planned versus having your battery get lazy and stab you in the back along the way. Again, I’ll get to this second key observation in a minute.
Tagging onto these primary observations regarding the navigation system, I have one other note and piece of advice that was stimulated by my drives as well as other news. This is something that anyone driving an electric vehicle and getting close to an empty battery would do well to understand. I’ll write about it a little more throughout this article, but the basic tip is simple: drive slowly to maximize your range, and definitely slow down if you think you’re cutting it close and could run out of electricity.
Before going further, let me just clarify what I’m talking about regarding “smart navigation.” This is the long-distance trip planner system Tesla rolled out a couple of years ago that CEO Elon Musk said would do away with range anxiety. The Tesla navigation system tells you how to get to your destination, how long it will take, and how far away it is, but it also does a few things that really make a driver’s day.
- It indicates where you need to Supercharge along the way (if you need to Supercharge along the way).
- It tells you how much battery charge you’ll have left at each Supercharger you need to stop at along the way and how much battery charge you’ll have left at your final destination. (As you drive, of course, those numbers can change.)
- It even goes so far as to warn you that you should slow down if it seems you are in a situation where you could drive yourself out of electricity. My colleague had this happen on the highway a couple of times, with our Tesla telling him he should drop his speed to 100 km/h to be safe. (I’ll explain how he got into such situations in a moment.)
One piece of good news from our first experiences using the smart navigation system is that it’s surprisingly accurate. Actually, it seems to lean toward being conservative … most of the time. Also, as I just wrote above but is worth repeating, if things do take a turn for the worse, the brilliant navigation system basically tells you how to not end up on the side of the road. (By the way, I recommend taking the car’s advice in such situations.)
Smart Navigation Surprises & Hypotheses
On my first long trip relying on the navigation’s intelligence, the Tesla system told me at the beginning of my trip that I’d arrive in Berlin with approximately 20% charge. I ended up arriving there with 23% charge.
On my trip to the Polish boonies, the navigation system told me at the starting line that I’d arrive with 60% charge. I ended up arriving there with 67% charge.
Clearly, these experiences have already given me a lot of confidence in the system’s ability to get me to practically any destination in a low-stress way. But what’s behind the results? What did I learn on these initial trips?
The navigation system is intelligent not only because it pays attention to the speeds of the roads you’re supposed to drive on and the type of Model S you have (two things which it would seem have to be in the calculation). It was pretty clear from my drives and my colleague’s drives that the navigation system takes into account several additional factors.
Speed — it’s not just a Sandra Bullock & Keanu Reeves movie
One factor I definitely noticed the navigation system pays attention to is your own recent driving profile (average energy use). It seems, in particular, that it pays attention to the last 50 kilometers (30 miles) of your driving … I think. Tesla didn’t want to reveal specifics, unfortunately (but understandably), but that’s my guess from paying attention to how the end-of-trip battery capacity estimates changed as key segments of my driving history moved off my energy graph screen — the display screen that shows the car’s energy usage over the last 50 kilometers (in the image below, the graph on the right with the orange line).
For example, on the first trip, I had significant spikes in energy usage when I accelerated quickly and then got up to ~150 km/h for a little while. Once those events moved off my display (once they were >50 kilometers behind me), my expected battery capacity at arrival grew. I noticed such shifts a few times, which led me to think that 50 kilometers (or 30 miles in the US?) is the driving history Tesla is tracking for its estimates.
The general point is: If you drive like a speed demon, the navigation system reduces your expected battery capacity at your coming destination. If you drive like my mom (or get stuck in slow-moving traffic on what should be a fast-moving highway), your expected battery capacity at your next stop rises.
I don’t know for sure if 50 kilometers is the extent of your driving history that the smart navigation considers when making its estimates, so don’t sue me if I misjudged and am off by a few kilometers (or a few thousand), but I did discover/confirm after coming to these conclusions that Tesla definitely does look at your driving history to some extent or another. The Tesla manual actually says (with emphasis added by me), “The estimate takes into account elevation changes and the expected driving speed based on the vehicle’s history.“
On either Tesla screen (the small one behind the steering wheel, pictured above, or the huge 17″ one), you can look at a graph of your Wh/km over the last 50 km driven to get a sense of what the navigation is based on, and you can also see your average Wh/km over that period. Of course, you should know whether you’ve been boosting “more than you should,” driving faster than average cars on the roads that you’ve been driving on, etc.
Speaking of the average speed of other cars, another factor I assume Tesla takes into account is the average speed of either Tesla drivers or some broader group of drivers on the routes you are driving on. If the navigation system just took into account posted speed limits (as I initially feared it might), it would have problems. On some roads, the average speed of traffic is much higher than posted. On other roads, the opposite is true. In Germany, there are those crazy Autobahn roads that absolutely destroy your Wh/km average. I couldn’t get much info out of Tesla, which apparently isn’t eager to reveal the chemistry to its navigation secret sauce, but I think the algorithm must include data on how fast “average drivers” drive on the roads you are planning to cruise on. I assume this goes beyond Tesla drivers in order to have a good sample size feeding in their data, but the possibilities here are a bit beyond my knowledge base, so I’d be curious to hear if anyone has more info or specific hypotheses.
In any case, the take-home point is the same as before: If you drive super fast, the estimated battery capacity at your destination is going to drop gradually (or quickly) as you move along the asphalt. If you chill out and take a Snoop Dogg approach, your estimated capacity at the end of your trip will rise. My experiences seemed to indicate that simply driving with the flow of traffic didn’t typically change the estimated arrival capacity, even if the flow of traffic was considerably faster than the posted speed limit.
By driving quite fast for a while on my first trip, I dropped my estimated arrival capacity from 21% to 15%. By driving more moderately again, I got it back up to 21% without too much trouble. Then horrible traffic coming into Berlin hit and my estimated capacity slowly got boosted up to 23%, which is what I had when I got to the Tesla service center (my destination). Note, however, that the traffic coming into Berlin wasn’t typical. I learned that this particular stretch of road where I was stuck in nearly immovable traffic for almost an hour was being repaved, reducing the highway to one lane for a significant stretch. According to a taxi driver I had in Berlin, this project began approximately one week before I hit the unfortunate surprise. Presumably, this road project hasn’t been in place long enough to fully update the Tesla navigation’s estimate for average speed of traffic on that stretch of the route. (Of course, that update is occurring gradually only if my hypothesis noted above is true and Tesla is tapping into actual driver speeds to help make its estimates.)
Elevation … and Weather
As the quote above from the Tesla manual indicates, the navigation system also considers elevation changes when estimating your eventual battery capacity at your destination(s). This is again something I was initially concerned the navigation didn’t take into account. I knew elevation changes could make a big difference in range, but I was only cautiously (or nervously) hopeful that Tesla’s navigation system had that level of sophistication. As it turns out, Tesla made a slick move by including elevation changes in the algorithm, and I would say this is one big reason why the navigation’s estimates are so surprisingly accurate.
Weather is not mentioned in the manual, but it’s another factor that I am convinced plays a notable part in estimating your battery capacity at arrival. First of all, we know Tesla’s cars are packed with sensors. Their batteries have to be monitored very closely, with temperature being a critical factor the car’s central intelligence system is obsessively watching. If the car knows the temperature inside and around its batteries, it can presumably feed that external temperature data to the navigation system as well so that it can make smarter (brilliant) estimates. The car apparently also has sensors that focus on whether or not your windshield is wet. I didn’t realize or remember this, but while driving home from Berlin, it started to rain a little … and my freakin’ windshield wipers turned themselves on! Rain is another factor that can really affect a car’s energy efficiency and range, so I presume the navigation system takes info from whatever sensors tell my windshield wipers to turn on and uses that information to make a more sophisticated estimate.
My buddy Jacek experienced the effect of weather a bit in the real world and seemingly validated my assumptions. He had the unfortunate luck of driving on some tight routes under heavy rain. At two of the departure points, the estimated arrival capacity looked good, so he set off onto the open road. However, seemingly due to the rain, the capacity estimates quickly dropped once he started driving. Presumably, it was increased resistance from rain that led to the drop, but I have to admit that the underlying details here are hard to envision clearly and I’d like to have some experience with harsh weather myself to confirm (or not) the importance of this factor. In the meantime, though, if it looks like it’s going to be rainy, it’s surely advisable to expect a notable drop in your battery capacity once you hit that rain.
Tips for Using Tesla’s Smart Navigation?
The first tip I have to offer is super obvious: Be more cautious than not on new routes and where your battery capacity is cutting it close. This isn’t because of any problems with Tesla’s navigation system, but just because you never know what the heck is in store. You could take a wrong turn and be in trouble if you aren’t too cautious. I took one wrong turn early in my first trip and my expected battery capacity at arrival changed from 20% to 15% immediately. This was right after Supercharging. My mistake left me driving on a fast highway in the wrong direction for several minutes and then having to make up my tracks. I was fine anyway, but the situation could have been much worse for me.
Tesla tells you at Superchargers along the way how much you should charge to arrive at your destination with no less than 10% battery capacity. I ignored that and charged to 99% so that I’d arrive in Berlin with a 20% charge. If I had taken Tesla’s advice this time (and still taken that wrong turn that I took), the smart navigation would have presumably told me I’d get to the Tesla service center with 5% charge (while I was still 3½ hours away and unsure of what surprises were ahead). That would have scared the bejeezus out of me. I was immediately happy I charged to 99% that time. Perhaps after a few more trips to Berlin I’ll feel more comfortable with an estimated 10% charge at arrival, but I’m not ready to make that leap just yet. I’d rather spend an extra 15 minutes or so at the Supercharger.
My second tip: Pay attention to your historical driving profile (your Wh/km graph for the past 50 kilometers). If it was full of crazy acceleration and you’re toning it down now, your navigation’s estimate is almost definitely going to be conservative. However, if you’ve been driving like someone trying to set a single-charge distance record and you’re going to need to step up the pace on your trip, the Tesla navigation probably isn’t reading your mind (yet) and is being optimistic with your estimated arrival capacity.
Frankly, in my first long drive using Tesla navigation, I formed a habit of obsessively watching my Wh/km graph and doing some crude calculations in my head to adjust my own expectations for battery capacity at arrival (and, more importantly, how much I could go wild on the highway and enjoy the power underneath the acceleration pedal of the Tesla).
My third tip: Pay attention to the weather. If rough weather is around the corner, expect that to slam your energy usage and expected battery capacity at arrival pretty hard. Also, drive in perfect weather as much as possible. 😉
Overall, it’s a huge relief to have Tesla’s brilliant navigation system at your fingertips. It’s even better than I expected, and I think it does go a long way in preventing any potential range anxiety. It’s another feather in Tesla’s hat that I have a hard time believing other automakers will match anytime soon. I’ll refrain from bashing some other electric models, but, yeah, Tesla’s leadership rocks. From a user’s perspective, it would be very hard to give up this smart navigation feature in a future electric car.