Previously, the top factor in buying a new car was reliability but now only 24 per cent of respondents cited this as the biggest influence on their car purchases.
The survey was conducted by AA Personal Loans, and chief executive officer Mark Huggins said: "Despite falling petrol costs, our first CPI [Car Purchase Index] report shows that the current financial climate is making people reconsider their options when buying a car, and looking for something cheaper to run is a good way for a family to economise."
After cost-effectiveness, the most influential reasons were the current car being too old, comfort and eco-friendliness.
Meanwhile, drivers have been advised that they may be able to keep costs down on insurance through regular vehicle maintenance.
Insurer RIAS has said that replacing worn windscreen wipers, cleaning lights and checking tyre pressure can help avoid motoring problems.
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