the british rail class 166 "network express turbo" diesel multiple units (also known as just "thames turbos" ) were built by abb at york works from 1992-93. these units are the express version of the class 165 "network turbo" units. they have a top speed of 90mph (suitable for mainline use), are carpeted throughout and have air-conditioning (the 165s lack the latter two features and it should be noted the 166 is similar to the class 158 in terms of what it offers).