The chassis used by Sebastian Vettel in the first four races of 2014 was bent, according to Germany's Auto Motor und Sport.
The reigning quadruple world champion notably struggled alongside fresh-faced teammate Daniel Ricciardo until Spain, where he spectacularly scythed through the field and declared for the first time that driving in 2014 is "fun".
"I do think it made a difference," the German declared after the race.
Auto Motor und Sport correspondent Michael Schmidt said further investigations have been taking place at Milton Keynes after Barcelona.
He confirmed: "The chassis he (Vettel) used in the first four races was in fact crooked."
Schmidt said Vettel, the winner of the last nine grands prix of 2013 on the trot, had suspected something was wrong with his car after China.
"A second down (to Ricciardo) was too much. I had not forgotten how to drive," said the German.
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