The car makers behind Formula One motor racing said they would form a rival championship.

ECONOMIST: Flying high

"While we welcome Michael Schumacher back to Formula One, the fact is any form of in-season circuit testing is strictly prohibited, a regulation clearly laid out by the FIA and adhered to by all of the teams, " said Williams in a statement.

CNN: Motorsport: Williams block Schu testing bid

Formula One is considered the most competitive and sophisticated form of motorsports.

FORBES: The Business Of A Formula One Team

At the Hungarian Grand Prix in 2009, Lewis Hamilton achieved the first historic victory for a Formula 1 vehicle featuring KERS hybrid technology in the form of the Mercedes-Benz KER System.

ENGADGET: Visualized: Mercedes-Benz SLS AMG E-Cell bares all

Formula One was planning to structure its Singapore IPO in the form of a stapled security, which includes a sale of both shares and loan notes.

WSJ: CVC May Revive Formula One Singapore IPO