Tesla Inc.’s Semi is headed for the grocery stores in Detroit Three automakers’ backyards. Meijer Inc. has reserved four Semi trucks for $5,000 deposits apiece, Dan Scherer, a fleet manager for the Grand Rapids, Michigan-based retailer, said at the product unveiling held Thursday at Tesla’s design studio near Los Angeles. He said the closely held company operates 220 trucks in six states in the Midwest. “Electric drivetrains are a proven technology,” Scherer said in an interview. “Electricity is cheaper fuel than diesel, and you are less dependent on the spot pricing of fossil fuel.”