Expensive semi-automated controls that encourage drivers to let their cars accelerate, brake, and steer for them have a high failure rate and offer car buyers no method to compare their accuracy, according to a preliminary round of tests conducted by the Insurance Institute for Highway Safety (IIHS).
The insurance-industry nonprofit tested five luxury cars: 2018 Tesla Model 3 and Volvo S90, 2017 BMW 5-series and Mercedes-Benz E-class, and a 2016 Tesla Model S. The agency compared the vehicles’ automated emergency braking, adaptive cruise control, and lane-keeping-assist features on a test track and on public roads. The results, both objectively and subjectively, largely mirrored our own test of semi-autonomous vehicles from 2016 in which we ran a 2015 Tesla Model S, a 2015 Infiniti Q50S, a 2015 Mercedes-Benz S65 AMG, and a 2016 BMW 750i through a consistent barrage of track and road evaluations.
Self-Driving inside the Lines
During testing on multilane highways outside the IIHS’s Vehicle Research Center proving ground in Ruckersville, Virginia, only the 2018 Tesla Model 3, which was equipped with Autopilot version 8.1, stayed completely within the lane markings in all but one of 36 runs. The IIHS tested each car six times on three different sections of curved highways and another six times on three different sections of hilly highways. Both sets of tests were intended to challenge the vehicle cameras when lane markings disappear from sight. In all, the IIHS ran 36 individual tests per car under the same speeds and conditions. The Model 3 only touched the lane markings on one hill but never crossed over or disengaged the system while driving.
By comparison, the 2016 Tesla Model S, with an older version of Autopilot 7.1 that uses a single camera instead of at least four as in the current model and in the Model 3, could only stay in its lane 28 percent of the time while driving uphill. It veered into the adjacent lane two-thirds of the time, the worst performance of any car in the test. However, on the curved-road test, the Model S went over the line only once, bettering all the cars except the Model 3.
Overall, the 2017 Mercedes-Benz E-class, equipped with Intelligent Drive, was the next-best performer. It kept in its lane half the time on curves and 83 percent of the time on hills. Next up was the 2018 Volvo S90 with PilotAssist, which stayed centered for just half the time on both road types. The BMW 5-series, equipped with Driving Assistant Plus, could only manage three runs staying fully within the lanes on curves, and it failed to work at all on hills.
When the E-class failed to keep centered, it was more apt to ride the lane divider rather than to cross it entirely; the S90 and 5-series were more likely to cross the line. Out of all 36 lane-keeping tests, the 5-series disengaged its system in 16 of them, significantly more than the E-class (two) and the S90 (four).
Automated Emergency Braking
Tests of the automated emergency braking system were performed on the IIHS track. Only the Teslas failed to brake in time for a simulated vehicle during an auto-braking test at 31 mph. In auto-braking tests with adaptive cruise control engaged, the Teslas did brake in time-earlier, in fact, than the European cars-no matter which setting for following distance was selected. In two more tests-one simulating a vehicle following a lead car that slows to a stop and accelerates, and another simulating a lead car that suddenly changes lanes to avoid a stopped car ahead-all the cars passed with flying colors.
Semi-autonomous capability is standard on the S90 and costs up to $10,200 on the E-class. On the 5-series, BMW charges $1700 for the Driving Assistance Plus package; depending on trim level, choosing it can also require buying another package of similar price. Tesla charges $5000 for Enhanced Autopilot on the Model 3 and Model S sedans.
In our tests from 2016, in which we recorded the number of lane-keeping-assist failures on a 50-mile public route, the Model S came in first and the BMW second. But while the IIHS has run a standard test for years to evaluate and compare auto-braking and collision-alert systems and included them in its safety rankings, there is no such test for adaptive cruise control or lane-keeping assist, the two features most critical for semi-autonomous systems.
“We’re not ready to say yet which company has the safest implementation of Level 2 driver assistance, but it’s important to note that none of these vehicles is capable of driving safely on its own,” IIHS chief research officer David Zuby said in a news release.
And to that we say, keep your hands on the wheel and your dog out of the driver’s seat.