Last year, we took a somewhat fraught road trip in our long-term Tesla Model S, attempting to use the company s Supercharger network to test the idea that anyone can hop into a Tesla and cross vast swaths of the country in it. We traveled from Michigan to Virginia and made it without being stranded, but it wasn t easy. We found plenty to fault in Tesla s navigation system, which used (and still uses) buggy and indecisive software in beta form to guide drivers to their destination using Superchargers as waypoints, even suggesting how much charging is necessary at each stop. Mixed with range anxiety the fear of running out of juice far from a power source the trip was both frustrating and stressful. In our postmortem on the experience, we noted that with more planning and a stronger familiarity with the Tesla s energy usage in different climates . . . a faster time is almost guaranteed. So precisely one year later, we applied lessons learned on that trip, as well as a year of pseudo Tesla ownership, to try it all over again but better.[1]
Planning, and More of It
Our annual Lightning Lap[2] track test at Virginia International Raceway provided the opportunity to make the same journey, in similar ambient temperatures (important because battery performance, and thus range, can be susceptible to temperature variations). Having already proved that the Tesla can cover long distances relying on the Supercharger network, this trip would be about minimizing charging time and exploring how another year and more than 20,000 miles of familiarity with our long-term Model S[3] might make us better at using it for a long trip. This time, we d plot our own battery-charging strategy rather than relying on Tesla s navigation system to handle that. Now more familiar with the Tesla s energy usage at highway speeds, we knew it could be capable of at least 200 miles given a full battery and the extra capacity unlocked by selecting the trip-mode charging limit. The overly cautious recharging strategy we employed last year was binned in favor of a more aggressive tactic that would run the battery as low as possible between Supercharger visits.
Superchargers fill a battery to 80 percent capacity in 30 to 40 minutes; it can take about the same amount of time to fill the remaining 20 percent, meaning each time we topped off the battery last year (an impulse born out of range anxiety), we were wasting time that could have been spent driving to the next charger. It might sound strange, but given that the fastest charging happens between empty and 80 percent full, you want to plan your Supercharger stops, and the amount of juice taken on at each stop, such that each successive charger is reached using as much of the available electricity as possible. It means a quicker, more productive recharge and less time spent parked along the way. To prove the strategy s soundness, we opted to hold to the same number of charging stops called for by the navigation system last year four with no panicked detours allowed. Why use the same system-chosen stops? Two reasons: First, to give our repeat journey a direct baseline for comparison; and second, because the navigation s poor decision-making becomes a factor only once you re on the move. The four scheduled charging stops from last year Macedonia, Ohio; Somerset, Pennsylvania; Woodbridge, Virginia; and South Hill, Virginia are ideally spaced, distance-wise, to execute our new maximum-mileage, efficient-recharge strategy.
Last year, those four stops turned into eight, thanks to the flawed beta-iteration Trip Planner programming. The planner is supposed to guide you to faraway destinations using Superchargers as waypoints and to suggest adequate charging levels at each one for reaching the subsequent charger. Except the system had a nasty habit of second-guessing itself after leaving a charger, which is what led it to suggest extraneous stops. It appears that the energy-intensive act of merging onto a highway throws off the system s range-to-empty prediction algorithm, triggering warnings of insufficient charge to reach the input destination. This can seem calamitous to the unaccustomed, but this time we d ignore the setup s calls to turn around and charge more after leaving a Supercharger, as we ve found that the prompts eventually fade as more miles are driven at a more efficient freeway cruise. In any case, this is how the repeat trip went, stop by stop:
Mile 0: We leave Ann Arbor s Supercharger at 3:45 p.m. with 240 miles of range showing, meaning the pack isn t quite full. Macedonia, Ohio, 181 miles away, is set as the lone destination on the Tesla s navigation system. We re only running the nav system to compare its input with our own strategy, and any suggestions it gives outside of route guidance will be ignored. Four stops only!
Mile 181: Less than three hours later, we roll in to Macedonia, Ohio, with 56 miles of indicated range. We plug in with the intention of taking on an 80 percent charge around 200 miles of indicated range. After grabbing a sandwich for dinner we come back to find the Tesla displaying 222 miles of indicated range. We quickly unplug and nose east toward Somerset, Pennsylvania, about 180 miles away.
Mile 361: Arriving in Somerset, we calculate that we have spent six hours and fifteen minutes driving and charging since leaving Ann Arbor. Last year, it took us more than seven hours to reach Pittsburgh, making this longer haul in less time feel like an accomplishment. Our strategy is paying off, and we have just 20 miles of range to spare before we plug in. Since Somerset is also our overnight stop, we let the car take on nearly a full charge to 243 miles of indicated range in preparation for the longest Supercharger-to-Supercharger jump of our journey, a 200-mile trek to Woodbridge, Virginia, the next day.
Mile 563: For the first time ever, our long-term Tesla cracks 200 miles between charges. That it does so and still displays 50 miles of available range when we stop in Woodbridge, Virginia, hints that it could go farther if driven the right way. We saw mostly 70-to-75-mph highway cruising between Somerset and Woodbridge, but were snarled in Washington, D.C. rush-hour traffic for about 40 miles, a boon for the Tesla s regen system that converts unwanted momentum to electricity for recharging the battery by operating the electric motors as generators when the vehicle is coasting or rolling to a stop. Our confidence is brimming, since last year the farthest we made it between stress-induced charging stops was a measly 161 miles. In any case, we juice up to an indicated 188 miles of range with a 35-minute charge, which should be more than enough to get us to South Hill, Virginia, 160 miles to the south.
Mile 725: It turns out we could have spent even less time charging in Woodbridge than we thought, as we arrive in South Hill with an indicated 31 miles of range left. We don t need much to make it the 75 miles to Virginia International Raceway, our final destination, and 13 minutes of charging yields an indicated 91 miles of range before we head out on the final leg.
Mile 803: Talk about squeakers! The Tesla displays just 13 miles of range when we deploy the Model S s 240-volt cable from the trunk and plug it into one of VIR s mobile-home hookups in the paddock next to pit lane. Still, even running down the car s range this low, we never felt as if the indicated range was falling at a rate massively out of step with the distance we were actually traveling. Last year, it took 17.5 hours to reach Virginia from Ann Arbor via the same route, not counting the time spent at an overnight stop in Pittsburgh. This time, using our newfangled strategy, it took only 15 hours and 48 minutes, again excluding an overnight stop. We stopped four fewer times to power up, and slashed our time spent sucking up electrons to only 2 hours and 56 minutes; the 1 hour and 23 minutes saved at this task relative to last year comprises nearly all of the difference in the overall travel times between the two voyages. Our goal was to summarize the trip in one sentence, but we whittled it down to a single word: better. Not once did we flirt with an empty battery and a call to Tesla roadside assistance. Nor did we encounter much stress at all, or any need to hypermile the Model S or cut back on our A/C use, and we spent far less time charging. The only deviation from the original route was moving our overnight stop from downtown Pittsburgh where we parked the Tesla without plugging it in, necessitating an unscheduled charging stop before reaching the city to ward off any potential overnight battery drain to a hotel next to the Superchargers in Somerset.
Might as Well Take a Lap
Just for fun, we added the Model S to our Lightning Lap roster and lapped it around VIR[4]. The big EV looked slightly less than graceful heaving its 5010 pounds around the course, and the computers restricted its power output less than halfway through its timed lap to keep the car s electrical system from overheating. Oh, well.
For the return trip, online staff photographer Michael Simari was convinced to tag along. With a driving partner in tow and the goal being to reach Ann Arbor the same day, we decided against retracing our steps from the southbound route, which deviates by more than 100 miles from the path gas-powered cars can take back to Michigan. Having proved our point that we could shave time off of our rookie Ann Arbor to Virginia trial, we wanted to explore how Tesla s Supercharger network has expanded in the past year and how it might help us get home quicker. Sure enough, we found two new Superchargers between Michigan and Virginia that, while still not on the direct route, are not nearly as far from the ideal trail. In yet another stunning display of the navigation system s poor decision-making, the new chargers didn t factor into its routing when we tried entering Ann Arbor as our destination, and the car insisted we follow the longer original route home. We ignored its advice and set out for the first new Supercharger, which was 124 miles away in Lexington, Virginia. After that stop, we d take a quick 109-mile hop to Strasburg, Virginia, before making a beeline for Somerset, Pennsylvania, where we d pick up the original scent home along I-80 by way of Macedonia, Ohio. We still faced four stops, but we d travel 88 fewer miles. As a bonus, the new route was far more scenic than the freeways we slogged south on, with twisting two-lane highways and hilly terrain gently loping through scenic western Virginia and Maryland.
The topography did give us our only range scare of the week, however, after too few electrons were loaded (we stretched our strategy of minimizing our charging time a bit too far) in Strasburg, which left us with, at one point, near parity between the Tesla s indicated range and the actual distance left before we reached the Supercharger in Somerset. Mr. Simari suggested we turn off the air conditioning to save range; this author was determined to use the A/C until we couldn t. With the climate control set at 70 degrees, we kept sweating until the indicated range stopped plummeting. We had reached the end of a long, gentle hill, and crawled into the Supercharger with just 14 miles of range to spare. A few hours later, we plugged the Tesla into its wall connection at the C/D offices. The new route had cut our travel time to 14 hours and 54 minutes just under an hour better than our improved time to VIR on the old path, and only about three hours longer than the trip takes in a gas-fed car traveling at normal speeds. Wouldn t you know it? A big chunk of that difference in travel times can be attributed to the 2 hours and 41 minutes we spent recharging on the way home, 15 fewer minutes than we had needed on the way to VIR.
Autopilot: It s a Thing, and We Used It
Confident in the recharging strategy, we turned our attention to Autopilot, the Tesla s semi-autonomous driving feature. Our Model S was assembled with Autopilot s sensing and vision equipment installed, but the software to run those bits didn t become available for over-the-air download until after last year s VIR trip. Our repeat trek afforded us ample time with Autopilot, which like the car s navigation system, is technically a beta product. Treat the system like a very capable adaptive cruise control meaning pay attention and remain engaged in the car s position relative to other cars on the road and the road itself and it s an excellent fatigue-reducer. Things get dicey when you let yourself be wiled by the car s seeming dexterity at driving itself. Psychologically, it s easy to be lulled into a sense of false security after using Autopilot for long periods without mishap. Watch it navigate a few tricky lane shifts in a construction zone, for example, or catch a car drifting into your lane, and it s easy to think it has everything handled. But then it misses something, prompting the system to beep frantically and beg the driver to intervene, a task made tricky by the rather muscular steering input required to overcome the car s grip on the wheel. If you re retaking control because, say, the Tesla lost track of the road markings and you need to guide it back into its lane, it s possible to overcorrect after wrestling the steering wheel to tell the system you want control, resulting in too much directional input.
On our final leg from Macedonia back to Car and Driver HQ, we tried to see how long we could go without needing to fully wrest control from or be given control by Autopilot. Leaving the Supercharger, we cued up Autopilot as soon as we cleared the tollbooth and merged onto I-80. We wouldn t shut the system off or need to retake control for another two hours and nearly 120 miles, and we only retook the helm in order to pull off and use the bathroom. Sounds great, right? Wrong. During the experiment, Autopilot failed us in a big way, one vaguely reminiscent of the fatal Tesla accident in Florida[5] that would come to light some weeks after our trip. As happened in that incident, our snafu involved the Tesla failing to see a semitractor-trailer and almost barreling into it. We were in the middle of three lanes and approaching the truck and trailer plodding along 15 to 20 mph slower than us in the rightmost lane with no other traffic nearby. With 50 yards between the vehicles (and closing), the truck drifted almost all the way into our path, the rig s driver drowsy or distracted. The truck didn t show up as an animated obstacle in the Tesla s digital gauge cluster as vehicles detected in the car s path should nor did Autopilot slow the car or emit a warning. Instead, we continued forward with no change in speed. Foot over the brake, ready to intervene, we slapped the turn-signal stalk to see what would happen. Without slowing, the Tesla smoothly steered itself in to the left lane, missing the truck. If the Tesla knew the truck was there, it didn t show it. The adaptive cruise control has a minimum following distance (a wider gap can be requested), which we were using, and we passed far closer to the truck than even that setting allows. Typically, the Tesla (and most of the adaptive cruise control equipped cars we ve used) will brake when approaching a slower-moving car, even when executing a lane change, in order to maintain the set distance to the vehicle ahead until the path forward is fully clear of obstacles. While we technically didn t retake control and Autopilot was never deactivated, had we not been paying attention and intervened, we faced the grim specter of meeting the rear end of a large truck in Ohio.
So what did we learn? It s difficult not to have reservations about Tesla s various beta features. Yes, there are warnings that appear when you activate Autopilot that you need to pay attention, but the system seemingly believes it s better than it is. Put another way, where Mercedes-Benz s similar system immediately yanks the driver back into the game at even the slightest tinge of doubt over a traffic scenario unfolding before it, it seems as though Autopilot tries to fill in the blanks right up until it can t. Tesla appears aware of the shortcoming, as it has announced a software update[6] that compels Autopilot to weigh inputs from the car s radar sensor as heavily as those from the forward-facing camera, which should help the system sense objects from farther away and react.
As for long-distance EV travel, Tesla s ever-growing network of Superchargers and its vehicles impressive (and expanding, with the introduction of the P90D and P100D models) all-electric driving range are certainly ready for a new type of customer, a more mainstream buyer like many of those hundreds of thousands waiting for a Model 3. Current Tesla owners skew wealthy, meaning they likely have an alternate vehicle supported by a nationwide refueling network with a century s head start on Tesla s Superchargers. The time may be approaching when a Tesla, even a Model 3, could serve as a family s only vehicle. We may have even reached it already, provided, of course, that the Joneses don t mind tacking on extra time for recharging on road trips or learning a few tricks for shortening those stops along the way.
References
^ a somewhat fraught road trip in our long-term Tesla Model S (blog.caranddriver.com)
^ Lightning Lap (www.caranddriver.com)
^ our long-term Model S (www.caranddriver.com)
^ lapped it around VIR (www.caranddriver.com)
^ the fatal Tesla accident in Florida (blog.caranddriver.com)
^ announced a software update (blog.caranddriver.com)