The British Rail Class 318 is an electric multiple unit (EMU) passenger train which operates in west central Scotland. The units were introduced on 29 September 1986 as part of the electrification of the Ayrshire Coast Line between Glasgow Central and Ayr/Ardrossan with alternating current (AC) overhead lines. Their use was extended to Largs in January 1987. They were also used on the Inverclyde Line in small numbers. The trains currently operate Argyle Line, Cathcart Circle Line, North Clyde Line, Whifflet Line and Inverclyde Line services. Following the withdrawal of the Class 314 fleet in 2019, these units are the oldest working EMUs in Scotland, having been in revenue-earning service for more than 37 years.

The Ayrshire Coast Line is one of the lines within the Strathclyde suburban rail network in Scotland. It has 26 stations and connects the Ayrshire coast to Glasgow. There are three branches, to Largs, Ardrossan Harbour and Ayr, all running into the high level at Glasgow Central.