The world's largest burger chain gets more than two-thirds of its business through the drive-thru, where it has made a number of small tweaks to improve service. But it's making big investments inside restaurants, as well. It announced last month it plans to roll out kiosk ordering stations and Bluetooth-enabled table service to all U.S. restaurants. The Oak Brook-based burger chain has nearly 500 redesigned restaurants around the country so far, including one in Chicago at Chicago Avenue and State Street that adopted the new concept earlier this year.