DETROIT (Reuters) - Ford Motor Co said on Thursday it faces a bill of up to $1 billion (£767 million) if Britain leaves the European Union without a deal, comprising World Trade Organization tariffs and the impact of a weaker pound.The impact of Brexit on Ford, based on internal calculations, would be in the range of $500 million to $1 billion depending on a variety of factors, Ford said in a statement.Sky News earlier on Thursday reported the hit could be $800 million.Car makers and other..