Four hundred miles with Tesla’s autopilot forced me to trust the machine
A few weeks ago, I finally tried Tesla Motors’ “autopilot” feature. A Tesla rep and Itooled around Houston’s I-45 in a Model X crossover SUV for 15 minutes, just longenough to test the vehicle’s adaptive cruise/automatic lane-keeping wizardry. Once Itoggled on the autopilot, the rep relaxed by checking e-mail on her phone. This senta clear message: keep an eye on the dumb journalist when he’s driving the$140,000 SUV, but once the machine takes over, everything’s fine.
As we pulled back into the showroom (or whatever Texas’ insane dealershipprotection laws demand Tesla call the places it’s not allowed to sell or servicevehicles), I told the rep that I was driving to Austin soon; Autopilot would be just thething for the long stretches of empty road out on I-10 and TX-71. Without missing abeat, she offered me a loaner Model S.
Ars has officially driven a Model S with autopilot before, but only under controlledcircumstances. The Austin trip would let me take the car out for nearly four hundredmiles of driving in a big mix of traffic scenarios. Plus, I’d get to log more cockpit timein a Tesla. Of course I said yes. Who wouldn’t?
My chariot
I’ve driven two previous Model S sedans on the approximately 400 mile (about 640km) Houston-Austin round trip—first a 2013 model P85+ and more recently a dual-motor P85D. Both trips were fun, since both times Teslaprovided the currently-most-powerful version of its sedan to hoon around in. True to form, the company againloaned me its top-end car: a dual-motor P90D with a 90kWh battery and the much ballyhooed “ludicrous mode“acceleration option (caution: there’s some NSFW language in that linked video).
The P90D looks and behaves much like previous Model S sedans. Its exterior is studded with sensors that candetect both the road and other vehicles, though unlike the P85D I drove, this P90D had the software installed totake full advantage of those sensors. (The entire Model S fleet produced with these extra sensors over the thepast year has since been software-upgraded to match the new vehicle’s capabilities.)
As I gingerly placed my butt in the matte leather driver’s seat of the pearly white P90D,another friendly Tesla rep gave me an unnecessary tour of the cockpit. Yes, I knew how theclimate control worked. Yes, I knew how to open the charge port. Yes, I knew how to engagethe auto-cruise and auto-steer. I was an old hand at Tesla-ing. Let’s get this show on theroad!
Perception, reality, and really good PR
My first jaunt was a 30-mile (48km) drive from the Houston Galleria showroom to my homeon the southeast side of town. Houston’s west 610 loop is in a constant state of rush hour,but the traffic mid-day was as light as it gets. It flowed along at maybe 40 miles per hour(64km/h) until the loop bent east and things opened up. Once I merged with traffic on theloop, I pulled the cruise stalk toward me twice to engage auto-cruise and auto-steer.
The car had already seen a 60mph (100km/h) speed limit sign, so it set that as its target speed. Since traffic wasmoving slower than the limit, my Tesla patiently paced the car ahead at a near-constant four car lengths. Itwisted the end of the cruise stalk forward and reduced that distance to two car lengths, which curbed theconstant flow of people jerking their cars angrily into the lane ahead of me (woe betide you if you leave a spacein Houston traffic). I forced myself to relax and hovered my hands over the wheel.
The car was driving itself. All I needed was a leather jacket and a two-way radio watch, and I’d be living out theKnight Rider fantasy I’d had since age 5.
Well, OK, this system isn’t revolutionary; adaptive cruise control (where your car paces itselfwith the car ahead) has existed for a decade or more, and automatic lane-keeping is at leastas old. Other car makers like Volvo, Mercedes, and Audi offer similar auto-cruise and auto-steer packages.
But if Tesla isn’t the first OEM to the autopilot table, it is certainly the loudest. The companydominates the marketing war—to the point that even folks who don’t particularly care aboutcars know the company’s story.
That evening, when I caught up with my next-door neighbor—not a particularly tech-centricperson—his eyes lit up. “That’s the electric car that drives itself, right?” he asked. He wanteda test drive.
The first leg: Getting out of town
I was due at my downtown Austin destination the next day at noon, so I set out at 7:30am with a fully chargedcar. From most points in Houston to most points in Austin takes three hours, but my trips begin with thedisadvantage of starting southeast of Houston and having to fight through the city’s morning rush hour (easilyadding an extra 60-90 minutes). I would also need at least 20-30 minutes at the Tesla Supercharger inColumbus, Texas to top off the battery.
For all the car’s software wizardry, calling its autopilot system an “autopilot system” isn’t really accurate. The caris very good at following the road and keeping pace with the car in front of it, but it does not follow the path youprogram into the navigation system nor do any other kind of advanced self-guidance. So even though Iprogrammed the Columbus Supercharger as my first destination, I stayed hands-on with the car as I drove out ofmy neighborhood and onto the I-45 service road. Auto-steer had to wait for the freeway, where I toggled it on.
Unfortunately, I toggled it right back off. The portion of I-45 near my home is undergoing a multi-year $6 billionrebuild, with a long stretch spanning several exits being destroyed, reconfigured, widened, and otherwise”improved.” The result is a multi-mile segment of road that snakes back and forth across what will eventually beboth sides of the finished project. For now, there’s no consistent surfacing, no real lane markers, and nothing forthe lane-keeping system to “see.” I drove human-style until I could bail off of I-45 and onto the westbound SamHouston Tollway.
Referred to by locals as “Beltway 8,” “the beltway,” or sometimes “the Houston Speedway” (people drive fast!),my section of the Sam Houston Tollway remains relatively un-cluttered for long stretches during the morning. Itoggled on the auto-cruise and auto-steer, dialed the target speed up to 90mph and the desired follow distance tofour cars, parked myself in the right lane, and pulled my hands slowly away from the wheel.
It takes a while to get used to this feeling. Instead of serving as the primary means of direction for a car, you’renow a meat-based backup and failsafe system. Instincts and impulses formed by more than two decades behindthe wheel scream out a warning—”GRAB THE WHEEL NOW OR YOU’LL DIE”—while the rational forebrainfights back. Eventually, the voices quiet as the car starts to prove itself. When the road curves, the car follows. Ifthe car is ever going too fast to negotiate the curve, it slows down and then accelerates smoothly back out of theturn.
Lane keeping was almost excellent. The car kept itself squarely planted in the middle of the lane without ping-ponging between the edges like some earlier systems did. The car would still sometimes “lunge” at exit rampswhen lane markings would fall away to the right or left, though the behavior was never enough to make me grabthe wheel and disengage. (Tesla’s 7.1 software update was supposed to eliminate the issue, though it hasn’tcompletely.) Other than the occasional lunge, however, the car was solid as long as there remained even theslightest trace of visible lane markings.
Sitting in the right lane on the tollway meant I frequently encountered other cars merging from the service road.Most of the time, the Model S would see them—with the speedometer display constantly updating to showsilhouettes of other cars in their approximate positions around me—and slow down. The braking was perhaps alittle later and a little harder than I would have done, but it was smooth and controlled every time. (The brakinginterval can be adjusted in the car’s settings). However, sometimes the person merging onto the road would bemore beside me than in front of me. In those cases, I could force the system to initiate an automatic lane changeby pushing up and holding the turn signal stalk, or I could scoot out of the way by manually mashing theaccelerator.
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