Ford Motor Co on Friday reported its biggest quarterly loss in over four years as it took $US2.5 billion ($A3.4 billion) in charges for job cuts and plant closings at the start of a massive restructuring effort. Excluding the anticipated charges, Ford's results fell short of Wall Street expectations, underscoring concerns about the weakness of its auto operations and sending its shares down as much as 6 per cent. Vehicle sales dropped by 6 per cent, reflecting steeper incentive spending, fewer sales of profitable sport utility vehicles and a greater reliance on low-margin sales to commercial fleets and car rental companies.