According to Official Guinness Records,
The longest ever horizontal power slide in a car lasted 2 hours 11 min 18 sec and was performed by Simon de Banke (UK) on 29 July 2001 at the MIRA Proving Ground, Nuneaton, Warwickshire, UK. Simon was driving a standard Subaru Impreza WRX 2001. The road surface was Bridgeport pebbles, which, when wet, are designed to have similar handling charateristics to compacted snow.
For a complete list of 2001 records, please visit 2001 Guinness Records in United Kingdom.