Three years ago this week, Tesla CEO Elon Musk presided over a spirited outdoor event that he called “Battery Day.” For years, Musk had teased plans to eventually introduce an affordable mass-market electric vehicle, and now, speaking to a parking lot full of honking fans sitting in Teslas, he explained how he would do it. For more than two hours, in a top-to-bottom reimagination of how to make EV batteries, Musk described new ways to mine and process nickel and lithium, manufacture electrodes, fashion battery cells and stack them in a pack. By 2023 or so, he said, the new approaches would halve the cost of batteries and allow Tesla to produce a $25,000 EV.

Today, the industry treats Battery Day as a coming-of-age moment in which Musk effectively warned rivals to sharply bring down costs or risk losing the EV race to more nimble competitors. And most responded: Volkswagen and BMW vowed that they, too, would cut battery costs by 50%. General Motors promised to slash its battery costs by about 40%. Dozens of companies sprang up to replicate the outsize battery Musk described—the 4680, a cell about twice the size of conventional cylindrical EV batteries, measuring 46 millimeters (1.8 inches) in diameter and 80 mm (3.1 in) in length. Others sought to perfect production methods such as dry battery electrodes, eliminating expensive traditional electrode-making equipment.

But the $25,000 Tesla—or the Model 2, as analysts call it—hasn’t arrived and doesn’t appear close to coming soon. The key to getting the price of an EV down is the battery, which can be 40% of a vehicle’s cost. Tesla has produced relatively small batches of the 4680—the company appears to be making enough of the cells at its Fremont, Calif., and Austin, Tex., gigafactories to manufacture about 75,000 Model Ys per year, a fraction of the 750,000 Model Ys that Tesla sold in 2022. And the early 4680s appear not to incorporate many of the changes Musk described on Battery Day—their cathodes do not use DBE, for instance, and their anodes do not include silicon, according to multiple independent teardowns of the battery.