The government is pressing to complete new rules on tax breaks for electric-vehicle purchases by an end-of-year deadline as auto companies seek guidelines that help qualify as many vehicles as possible. The Treasury Department is leading the effort after the August signing of a law that extended an existing $7,500 tax credit through 2032. The EV plan, included in Democrats’ climate, health and tax-policy package known as the Inflation Reduction Act, included new requirements for U.S. battery sourcing that auto makers have warned will make it difficult for models available today to be eligible.