The scope for reduction of aerodynamic drag of passenger cars by ''add-on'' devices has been examined by MIRA in a study sponsored by the U.K. Government. On a car of the popular "hatch-back" style the drag was reduced by up to 31 per cent by this means without detriment to other aerodynamic characteristics. Fuel consumption tests with a similar car showed that with a combination of "add-on'' devices giving a 14 per cent drag reduction an overall fuel saving of 6 per cent could be obtained in mixed road conditions.
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