Gas savings...

Heard an interesting tidbit on NPR the other day about the gasoline savings reaped by replacing certain vehicles. Basically, the question was posed as what is better: replacing a 10mpg car with a 15mpg car, or replace a 20mpg car with a 50mpg car.

On the surface it seems that the latter is better, 30mpg improvement, whereas the first one only had 5mpg. However, when you think about the gasoline that is required for these two vehicles over a set distance, let's say 100,000 miles, the result is that the jump from 10mpg-->15mpg results in a savings of 333gallons, while the jump from 20mpg-->50mpg results in a savings of just 300gallons.

To visualize this, I plotted the incremental savings of gasoline required for 100,000miles vs the mpg. As you can see the dropoff is very steep at first, so the savings is large when changing from a lower mpg car. The takeaway from this is that changing from a hummer to a minivan might be just as helpful as switching from a civic to a hybird.