20 gallons cost $62.40. This would take the 20.2 miles per gallon car 404 miles, but would take the 24.9 mpg car 498 miles. So the more economical car gets 94 more miles for the same amount of fuel. This is equivalent to 94/24.9= 3.7751 gallons. At $3.12 a gallon this saves $11.78 a week.