How Ford's Sierra Cosworth went from £20,000 eighties boy racer to prized collector's item worth £200,000 today
The most affluent classic car collectors typically duke it out in auction rooms to get their hands on the rarest, most exclusive and desired models from past eras. Aston Martin, Bugatti, Bentley, Ferrari, Jaguar, Lamborghini, Porsche, Rolls-Royce: just …