Imagine shopping at a 100,000-square-foot big box without leaving your car. That's the vision New Mexico startup AutoCart LLC has for a drive-thru superstore it hopes to open in the Southwest next year. It has narrowed its site choices to Albuquerque, N.M., or Tucson, Ariz. Orders for products from 17 categories, including brand-name groceries,supplies and game rentals, will be taken at 30 stations. AutoCart's designers say the center can handle 600 cars per hour. Goods can also be pre-ordered through e-mail or fax.