8)* Buy a new car
If your vehicle isn’t becoming any more efficient after servicing, then maybe it’s time to think about getting another. It may seem counterproductive to spend money to save money, but buying a new car will save you money on fuel, tax and insurance. A new vehicle worth in the region of £10,000** could save you up to £12 a week on fuel.
Most of the suggestions are perfectly sensible. I've checked the figures, and yes, you can save about £500 a year on petrol if you replace a car doing 40 mpg with one doing 60 mpg (assuming 10,000 miles per year etc). The savings get proportionately smaller the more efficient cars are - going from 60 mpg to 80 mpg only saves £230 a year; going from 80 mpg to 100 mpg only saves £140 and so on.
IMHO, an annual saving of £500 on petrol does not justify buying a new car. You lose three-quarters of the value of the new car over the next ten years while saying £5,000 in petrol. That is just nonsense.
* Yes, they actually list ten ways to cut your fuel consumption, thus making a mockery of the headline.
** You don't get much of a new car for £10,000, do you? Half an MX5, one-third of a Ford Kuga etc. My approach is, wait for ten or fifteen years and buy one at a 80% – 90% discount to original list price.