With gas costing $4 per gallon:

Cost per mile of 30 MPG car = $4/30 miles =~ 13.3 cents per
mile
Cost per mile of 25 MPG car = $4/25 miles = 16.0 cents per
mile

Per mile savings of 30 MPG car =~ 2.7 cents per mile

<elodie.gillain@gmail.com> wrote
> Dear Forumers,
>
> Say I can choose between two cars. The gas mileage of the
> first car is
> 25. The gas mileage of the second car is 30. Let us say
> that the cost
> of gas is 4$ per gallon.
>
> The difference in gas mileage between the two cars is 5.
> So the
> savings if I choose the leaner car is 4$ per gallon/5miles
> per
> gallon=0.8 $ per mile
> Am I right?
>
> I greatly appreciate your help.
>
>
>