Reading
We test 60-0 mph panic stops because it's an important safety criteria. Cars that can stop in a shorter distance are less likely to rear-end the car ahead. In cases where a crash is inevitable, they can bleed off more speed before contact is made. Besides the brakes themselves, three criteria affect braking performance: the grip available from the tires, the surface friction and quality of the road, and the proficiency of the antilock brake system (ABS).
Our initial 2017 Tesla Model 3 full-ABS panic-stop measurement of 133 feet was indeed below average. But it didn't seem outrageous, especially given the characteristics of the standard 18-inch tires. They're hard (with a treadwear rating of 500), they run at an abnormally high tire pressure (45 psi), and their 235 mm tread width isn't generous considering the car's 3,884 pounds of weight. It all seemed to fit, but that was before Consumer Reports reported a 60-0 mph stopping distance of 152 feet, nearly 20 feet longer than ours.
Location is the main difference between our tests. Our Southern California track is smooth and well cared for. Consumer Reports' test track is in Connecticut, where there's real winter. It isn't open to the public, but I'm imagining it has a suitably grippy surface that is looked after. But with a certain amount of unevenness and maybe even a few cracks brought about by the rigors of winter, CR's has the inevitable surface irregularities we know our track doesn't have.
I didn't suspect ABS calibration after our test because, frankly, that's hard to screw up. And the obvious safety implication involved means that ABS calibrations are typically optimized to the nth degree before a car goes on sale. But ABS tuning nevertheless seemed more likely after Consumer Reports announced its alarming figures, especially considering my suspicions about its track. Tesla removed any remaining doubt by announcing the imminent release of a new over-the-air firmware update that it said would address the issue.
