BTCC series organisers have decided to keep Swindon Engines as the producers of the stock TOCA engines, extending the deal with the company until 2021.
Under the new contract, Swindon Engines will develop a new-spec engine, with the aim of introducing it ahead of the 2017 season of the championship.
"We are extremely proud to be able to continue our long-standing partnership with the BTCC, the UK’s highest profile motor sport series," said Swindon Engines managing director Raphael Caille.
"We have continued to develop our one-fits-all product over the last five years and provide a high-performing, reliable and consistent unit, which benefits teams throughout the grid.
"We will continue to provide the teams with the highest level of service, reliability and engineering."
Of the 32 cars that have contested the series this season, 19 have used the TOCA engines - including the cars of teams' championship leaders BMR and MG's factory squad.
"As we witnessed with the recent chassis, suspension and associated components tender, awarding this contract was certainly not merely a foregone conclusion for an existing supplier," said series boss Alan Gow of Swindon Engines' re-signing.
"Their tender and presentation was of the highest calibre and they were clearly voted for by a BTCC review panel, which included personnel from teams that use the TOCA engine and others that use their own power units."