A 2004 McLaren powered by the Mercedes-Ilmor 3.0 litre V10
Ilmor was founded by Mario Illien and Paul Morgan in 1983, as an independent British Formula One engine manufacturer. The company name was taken from the surnames of the founders. It originally started building engines for IndyCars with the money of IndyCar team owner and chassis manufacturer Roger Penske.
Daimler-Benz acquired General Motors' 25% share of Ilmor in 1993. In 2002, Daimler AG increased its share to 55% and renamed the company Mercedes-Ilmor. In 2005, Daimler became the sole owner of Ilmor and renamed the company first to Mercedes-Benz High Performance Engines, then to Mercedes-Benz HighPerformanceEngines. In December 2011, the company was renamed to Mercedes AMG High Performance Powertrains along with the renaming of Mercedes GP to incorporate the Mercedes-AMG brand.
At the same time, the small Special Projects part of the company, which between 2003 and 2005 had been contracted to co-develop, arrangement, preparation and tune up Honda's IndyCar Series engines until 2011, split away to become a separate company, owned by Mario Illien and Roger Penske. This new company, which is totally independent of Mercedes, is once again known as Ilmor Engineering Ltd.