2016 Tesla Model X: Math, Befuddled Software and Chasing A Mirai to Lake Tahoe
by Jason Kavanagh, Engineering Editor on September 28, 2016
I'm on my way north from Santa Monica in our long-term 2016 Tesla Model X, "chasing" (har har) Dan Edmunds in the Mirai. We're headed to Lake Tahoe. Same route. No combustion.
Things have changed. When I last road-tripped a Tesla, it was our old Model S a couple of years ago. At the time, not only was the Supercharger network less developed than it is now, but the on-board software wasn't as capable.
Back then, the onus was entirely on the driver (or passenger, if you are so equipped) to do the math of when to stop to charge, and for how long. If you're trying to minimize your downtime on a long trip, you end up constantly assessing your current rate of consumption and adjusting your driving style as needed so that you arrive at each Supercharger with as little juice in the tank as possible. This minimizes your time spent recharging.
But there's an element of stress at play. If you're playing this game right, you're rolling into each Supercharger with as close to zero miles remaining in the tank as your confidence allows. If you forget to, say, carry the two, you could end up stranded on the side of the road.
Today, it's easier. Or is it?
These days, if you program a destination into a Tesla's nav system, the car automatically does the thinking for you. It figures out all of your stops in advance. It plots your route among the relevant Superchargers and tells you how long to charge. It calculates how long it will take to charge given your current and estimated state of charge and attempts to minimize your time at each charger.
Crucially, it also knows how severe the terrain is en route to your next charging opportunity. For example, if there's mega-tall hill looming on the next leg, it'll make sure you stay at the charger longer to take on the extra juice you'll need to ascend it.
This all sounds brilliant, except I quickly find I can't trust the system. To wit, it wants me to make my first stop at the Buttonwillow Supercharger, even though I have enough range to skip Buttonwillow (125 miles from my origin) and still easily make it to the next Supercharger at Harris Ranch (another 75 miles). But I stop at Buttonwillow anyway, putting my trust in the system for the sake of science.
Ten minutes of charging at Buttonwillow is all it wants. Hmm. I continue on my way north on Interstate 5.
Within a mile, the nav system starts imploring me to turn around and recharge again at the Buttonwillow Supercharger. Yes, the one I just left minutes ago. Nuts. I stay the course on the assumption that it will figure out it's talking nonsense.
Eventually, it does figure out it's talking nonsense and instead plots a course to the Harris Ranch Supercharger. I recharge at Harris Ranch for thirty minutes and when I get back on the freeway, the nav system returns to nonsense mode, insisting I reverse direction and re-recharge at Harris Ranch.
For miles and miles it continues to insist I return to Harris Ranch, despite having plenty of range to reach my next Supercharger stop 133 miles away in Manteca. Finally, 68 miles out of Harris Ranch, it snaps out of its dumb insistence on going backwards and remaps the route.
Then it gets weirder. Instead of going to Manteca, it maps a route west through the Gilroy and San Jose Superchargers before heading east again. This would add 80 miles!
Yeah. I give up on the nav's instructions at that point.
As for other road-trip observations, the Tesla's abundant power is nice on paper, but it's largely irrelevant on a trip like this. When you're trying to make time in a Tesla, going fast can actually be slower than going slower due to the additional time needed at the charger. You don't really have the luxury of going your desired speed, whatever it is. But, man, it sure is nice to have the reserve power in an emergency situation.
Let's talk Autopilot. It's a mixed bag. On these roads it tends to drop out with some regularity where the lane markings fade. It doesn't always respond to a lane change request, either, and tends to "carom" within the lane when traveling straight, constantly searching for the edges like an underdamped system. Autopilot is a neat parlor trick and allows for some variety (which can be refreshing on a long trip), but autonomous driving it ain't.
Needless to say, my "extra" stop at Buttonwillow was superfluous and cost me ten minutes of charging, plus the associated transit and parking time. It's pretty clear that Dan's going to sail to victory on this voyage anyway, based simply on the basics of range and refueling time for each car. But I want to minimize his margin of victory, and the Buttonwillow stop really sticks in my craw. Whinge, whinge.
At one point later in the trip, Dan texts me his location. He's in Silver Fork. Fifteen minutes later, I'm in Folsom. My hope for a gracious loss goes down the toilet when I look up Silver Fork on a map. It's 55 miles away. I still need to Supercharge in Folsom.
I pick up my pace for the last leg between Folsom and our destination (Basecamp Hotel in South Lake Tahoe), just to feel like I did something to minimize the drubbing. Besides, I don't need to conserve juice anymore. I can plug in at the hotel and the car will have full (or nearly full) range in the morning. Try doing that with hydrogen.
When I pull into the hotel parking lot and ask Dan how long he's been there, the answer makes me wince: "Ninety minutes."
As if to rub salt in the wound, I went to retrieve my bag from the backseat area and was reminded of the Model X's worst "feature."
Jason Kavanagh, Engineering Editor