Pic, distribbed by Universal in the U.S., follows the ruthless rivalry between premier Formula One drivers, the late James Hunt and Niki Lauda.
Chris Hemsworth in pole position, qualifying talent Daniel Bruhl, Olivia Wilde and helmer Ron Howard, joined the red carpet grid to complete a formation-lap, greeting spectators en route.
Tasked to play Lauda, Bruhl (pictured above right with Howard) divulged the pair's initially awkward conversation.
"Niki called me at 6 o'clock in the morning, saying, 'I guess we have to meet now. Well, just bring hand luggage to Vienna, in case we don't like each other, then you can piss off right away.'"
The road to making the pic was less bumpy than anticipated. "I had to buy more clothes, because I stayed longer than expected," Bruhl said.
Formula One supremo Bernie Ecclestone completed his own Leicester Square circuit, with current Formula One drivers Sergio Perez and Jenson Button in tow.
Post premiere, guests revved over to One Marylebone to spray champagne into the night.
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