The saga of engine suppliers in the series has been a convoluted one. During its inaugural season in 1996, carry-over engines from CART were allowed, but were replaced the following season by naturally-aspirated V8s provided by General Motors (under the Oldsmobile Aurora name) and Nissan (bearing Infiniti livery). Toyota and Honda came on board in 2003, while GM rebadged its program under Chevrolet as Oldsmobile was being shut down. Three years later Honda got the exclusive and has been supplying all the teams on the grid since, but that contract is nearing its end.
In its place, the IRL has issued a new open formula in the hope of drawing a diverse array of manufacturers to the series. For the first time since splitting with CART (with which it has since reunited), IndyCars will race under turbocharged power. Ethanol will continue to fuel the series, but beyond that, teams and engine suppliers will be free to use as many as six cylinders (in whatever configuration they choose), with displacements not exceeding 2.4 liters and power ranging between 550 and 700 horsepower.
The use of turbocharging and the variety of configurations allowed under the new formula should make for some interesting racing, and we'll be waiting to see which manufacturers jump – or pass – at the opportunity.