Earlier this year, American automaker Tesla rolled out its new Summon feature to the company’s high-end electric Model S sedan. Tesla said this feature offers “increased safety and convenience.” It allows the Model S to drive itself up to 33 feet at very slow speeds in order to enter or leave a narrow parking spot or crowded home garage—without anyone inside the car. The operator must be within 10 feet of the vehicle, according to Tesla.

Summon was included in the Tesla Version 7.1 software update, which was automatically sent out wirelessly to all Model S vehicles, including Consumer Reports’ P85D test car. We’ve tried the feature, and found it can be useful, but we also felt that Tesla’s implementation posed an avoidable safety concern of the car potentially having low-speed impact with objects or walls. We contacted Tesla about our findings and the company has agreed to update the system to make it safer. 

Why Is Summon Mode Important?

Summon allows the Model S to be operated by remote control when the car is moving at very low speeds of around 1 mph, driving into your garage and closing the door, or opening the garage door and driving out. (This presumes your automatic garage door system can be operated using the HomeLink standard.)

Summon also can enable the Tesla Model S to pull in or out of a tight parking spot without a driver. That could save the driver from, say, accidentally dinging another vehicle when opening the door. This is particularly helpful considering the width of the Tesla Model S (2 inches wider than a Mercedes-Benz S-Class; 6 inches wider than a Honda Civic), which can make compact parking spaces even trickier to navigate.

Summon is relatively simple in concept, but it is an important harbinger of things to come. Self-parking functionality is one of a handful of emerging technologies that is paving the way to a future state of fully autonomous cars, and Tesla has made a point of pushing the envelope by allowing the car to, in limited circumstances, operate without a driver. At Consumer Reports, we consider it part of our mission to test emerging automotive technologies first hand as soon as they become available—and such autonomous features are a primary reason we bought our Tesla Model S P85D last year.

For instance, we were among the first to use Tesla's "AutoPilot"—a semi-autonomous system that enables the Model S to steer itself to stay in its lane. While we found it useful on the highway, we found that it struggled on secondary roads with unclear lane markings. We cautioned that in those situations, the system should not allow itself to be operated.

With a software update earlier this year, Tesla made changes to restrict its use on residential roads and roads without a center divider—a move in the right direction. When we tried the new Summon feature recently, the initial implementation gave us pause as well.  

How Summon Mode Works

Summon mode is clearly labelled "Beta" and needs to be turned on in the Model S’s on-screen “Autopilot” menu by the owner before it can be used. The user also has to enable “Allow Narrow Spaces” before the vehicle will attempt to tuck into tight spots on its own, and Tesla warns that “Using Summon to park in narrow spaces...increases the risk of damage to your vehicle.”

Summon initially was designed to operate with a key fob or Tesla smartphone app—and we tried out both. To use the key fob, we held down the top button until the hazard lights went on, and then pressed either the front or the rear of the fob to move the car forward or backward. Pressing any button on the fob stopped the vehicle. The smartphone app worked similarly. A tap on an on-screen button to begin movement, a tap to stop it.

We tried Summon Mode as a consumer would. Parking it in a narrow-width garage at one of our testers’ homes, and setting up obstacles at our Connecticut auto testing facility to see if the Model S would detect and avoid them. 

What We Found

As we used the system, we became concerned that, in an emergency, a user might not be able stop the car right away if they were to press the wrong part of the key fob (the buttons are not marked) or if they dropped the key fob. The operation of Tesla’s app when we tried it on an iPhone 6S had issues too. When we closed the app with the car in motion (something that might happen accidentally), the car continued to move.

There are fail-safes. The vehicle will stop if it encounters an obstacle that requires additional torque from the motor, a curb, for instance. The vehicle also will stop if anyone touches a door handle, though Tesla didn’t inform car owners of this. Sensors on the vehicle are designed to stop the car if it detects an obstacle in its path. However, the sensors do have blind-spots and cannot see all objects, so it is critical to be vigilant when using this feature, especially if you have children or pets.

When you first enable the feature, a popup screen states that the Summon system may not detect obstacles that are very narrow, or placed very low or high. Our evaluation bore that out. We tried out the Model S P85D with several large objects that a homeowner might leave in a driveway or on the floor of a garage—such as a duffel bag and bicycle—and the car failed to stop before hitting them. One of our testers also damaged one of the car’s 21" wheels against a curb in his garage when using the Summon mode after he was unable to stop it in time. Obviously, Tesla doesn’t intend for the Model S to be used in Summon mode unsupervised, but if the car cannot be relied upon to stop itself to avoid any obstacle, then it must have a foolproof way for the user to apply the brakes remotely.  

Tesla Responds To Consumer Reports

Because of the slow speeds involved, we see these safety concerns as posing a relatively low risk, but the risk is unnecessary. Why? Because Tesla could still offer the Summon functionality on the Model S, but design its controls to operate as a “dead-man’s” switch—thus requiring constant tactile engagement from the user to operate. If you dropped the fob, with a dead man’s control, the car would halt. Other consumer-operated machines, such as lawnmowers, are routinely designed with dead man’s controls to ensure safe operation.

For Tesla, a similar implementation would require the user to hold down the button on the key fob or app while the car is in motion. Simply letting go would stop the vehicle. BMW has a remote-control parking feature on the 7-Series in Europe, but it requires the user to continue holding the key fob for the vehicle to move.

As is our normal practice when we have a safety concern, we contacted the manufacturer and described our findings. Tesla got back to us quickly and said that its engineers had examined the issue and had worked out a fix. A new software upgrade to be deployed later this week will limit the Summon operation to the smartphone app and require the user to keep his or her finger on the phone screen—essentially operating it as a dead man’s switch. While you can’t initiate operation of Summon with the key fob—you can stop the vehicle moving by touching a button on the fob.

Tesla also provided us with this statement:

“Summon is an important step towards a safer autonomous future. Since introducing Summon just four weeks ago, our customers have used it hundreds of thousands of times safely and successfully. As a beta feature, we continue to test Summon and collect feedback from real-world user experience. Consumer Reports surfaced valid concerns that we’ve already built fixes for, continuing to make Summon and our vehicles better.”

Assuming the fix works as described, we expect it should resolve the issue, while still maintaining this convenient function on the Model S, and we applaud the speed at which Tesla sought to address our concerns.

Until cars are truly autonomous and and can detect all obstacles, we'd like to see such safety mechanisms become standard on future vehicles that employ any remote-control operation, starting from launch. That’s a win for consumers—cutting-edge functionality that puts a priority on safety.