Four environmental groups that want the U.S. Postal Service to buy more electric delivery vehicles are suing to halt purchases of thousands of gas-powered trucks as the agency modernizes its mail delivery fleet. The lawsuit, filed Thursday in federal court in California asks a judge to order the Postal Service to conduct a more thorough environmental review before moving forward with the next-generation delivery vehicle program. Plaintiffs contend that purchases of fossil fuel-powered delivery vehicles will cause environmental harm for decades to come. “Louis DeJoy’s gas-guzzling fleet guarantees decades of pollution with every postcard and package,” said Scott Hochberg, an...