Worked example
At 10,000 miles per year and 145p/litre, improving from 35 MPG to 50 MPG saves roughly £570 a year in fuel.
Frequently asked questions
Can I compare petrol and diesel?
Yes, but if prices differ, run each scenario separately or use the relevant typical price.
Does a more efficient car always save money overall?
No. Purchase price, finance, depreciation and maintenance also matter.