Wiktionary
n. The fifth and typically highest gear of an engine.
Wikipedia
Fifth Gear is a British motoring television magazine series. Originally shown on Channel 5 from 2002 to 2011. From 2012 until 2015, the show has only been available on limited distribution platforms such as Discovery from 2012 to 2014 and History since 2015, alongside ITV4 meaning the show is returning to Freeview for the first time in four years after it ended on Channel 5 in 2011. The show is currently presented by Tiff Needell, Vicki Butler-Henderson and Jonny Smith. Fifth Gear's rival shows are BBC Two's Top Gear and Jeremy Clarkson, Richard Hammond and James May's 2016 series The Grand Tour for Amazon Video.
Fifth Gear was first broadcast on 8 April 2002 as 5th Gear, and as a continuation of the original incarnation of the BBC show Top Gear, which was cancelled in 2001. Top Gear was relaunched later that year; Channel 5 originally wanted to carry on using the Top Gear name, but the BBC refused. Several of Top Gear's ex-presenters, including Quentin Willson, Tiff Needell, and Vicki Butler-Henderson, were hired by Channel 5 to present the series. The show's name was restyled as Fifth Gear in 2005. Needell announced the show's second cancellation on 24 May 2016 due to lack of funding.
Repeats of Fifth Gear also started being broadcast on UKTV channel Dave in April 2008 and later on Discovery Turbo.