A one-off, non-cash special item of US$12.4bn "for the release of almost all of the valuation allowance against the company's net deferred tax assets" helped boost Ford's 2011 net profit $13.7bn to 20.2bn, or $4.94 per share. Pre-tax operating profit rose $463m to $8.8bn "as strong performance in North America and Ford Credit offset challenges in other parts of the world", the automaker said on Friday.