Paul di Resta will return to Formula 1 as a reserve driver for the Williams team for 2016, the Grove-based squad confirmed on Monday.
The 29-year-old Scot left grand prix racing after the end of the 2013 season, having spent three seasons racing with Force India.
Di Resta returned to the DTM - where he took the title in 2010 - with Mercedes, with which he will continue racing this year, combining that with his role at Williams.
"I am delighted to be joining Williams as reserve driver and look forward to the 2016 season," said di Resta.
"It will be a busy year combining both driving in DTM with Mercedes AMG, and attending the Formula 1 grands prix in my new reserve driver role.
"I will be giving my full support to both and look forward to the exciting possibilities the year has ahead. I would like to thank Claire and Williams for the opportunity to be part of the team."
Williams said di Resta will "spend extensive time" with it at races and will also have time in the simulator to be ready in case he needs to replace one of the racing drivers.
"We are delighted to welcome someone with Paul's experience to the team," said Claire Williams. "Having competed in 58 Formula 1 races throughout his career Paul's racing knowledge will be invaluable.
"We are also confident that given his recent Formula 1 and current DTM experience Paul will be able to confidently step into the FW38 and assist with our 2016 campaign."