Automakers are making good progress toward a voluntary goal of including automatic emergency braking on new cars, but some companies are doing better than others. That's the conclusion of an update from the Insurance Institute for Highway Safety (IIHS) released Wednesday, which found that Mercedes-Benz, Volvo and Tesla now sell the highest percentage of new cars equipped with AEB.Mercedes had among the highest penetration of AEB on its new cars, IIHS said. Mercedes-Benz A total of 20 automakers, accounting for roughly 99 percent of all US-market new cars, agreed to equip every new passenger car with AEB, also known as precollision braking, by September 1, 2022. It's a voluntary commitment, but one with huge potential benefits: IIHS estimates that by 2025, this effort will prevent 28,000 crashes and 12,000 injuries on US roads.In the latest report, IIHS says that about half of all cars made by the 20 manufacturers between September 1, 2017 and August 31, 2018 were equipped with AEB. That's up from "less than a third" of cars a year prior.By percentages, Mercedes-Benz, Volvo and Tesla all exceeded 93-percent penetration of AEB on new models, IIHS says, with Tesla actually at a full 100 percent. In terms of raw volume, on the other hand, Toyota led with 2.2 million of 2.5 million vehicles (90 percent) built with AEB. Nissan was close behind, with 1.1 million vehicles (78 percent) so equipped, and Honda was in third place by volume at 980,000 cars, or 61 percent of volume.However, there's still a way to go. Ford, Mitsubishi and Porsche reported that fewer than 10 percent of their vehicles were equipped with AEB during the time period, and Jaguar Land Rover didn't report that any models were.IIHS also looks at which carmakers included AEB as standard equipment on their models, finding that, for 13 of the 20 automakers, AEB is standard "on all trim levels on at least half of their 2019 models." Notable exceptions, per IIHS, include General Motors, FCA and Mitsubishi, all of which reported having zero percent of new 2019 models equipped with AEB as standard.