In 1994, Al Unser, Jr. won the Indianapolis 500 with a Penske-Mercedes IndyCar. The engines were developed and built by Ilmor, but were badged as Mercedes-Benz. Ilmor which, realizing that a loophole in the rules for production-based engines would include any pushrod engine, built a very unusual purpose-built pushrod engine with a significant power advantage. This was done knowing that the "forgotten" loophole would be closed immediately after they took advantage of it, and so the engine would in fact be usable only for this single race.