noun
BAD : Over eighty per cent of these cars are old, and so are their machines.
GOOD : Over eighty per cent of these cars are old, and so are their engines.
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machine = a piece of equipment which performs useful work, such as a sewing machine, washing machine, or computer: 'To operate this machine, simply select the type of coffee you require and press the green button.' 'The latest machines can run both types of software.'
engine = a device which provides the power for a motor vehicle, train, aircraft etc: 'It was difficult to make yourself heard above the roar of the engines.' 'Check the tyre pressures and top up the engine oil.'