Physics Fun: How Many Elephants of Stuff Comes Out of the Tailpipe of Your Car?

We fill up our automobiles at the pump daily. Have you ever thought about how much of the stuff your car uses as fuel escapes from the tailpipe every year?  For a bit of fun, let's measure it in elephants per year.

Before we calculate this, we need to know a few conversion factors to help create our elephant equation:

• Gasoline weighs about 6 pounds (lbs) per gallon
• The weight of an elephant is about 10000 lbs per gallon

Now we can use the handy-dandy dimensional analysis we learned in our science classes to create a rough model that cancels out conversion factors. In the below equation q = Odometer reading in miles/week, and u = Mileage in miles/gallon.

? elephants = (q miles/1 week)*(1 gallon/u miles)*(6 lbs/1 gallon)*(1 elephant/10000 lbs)*(52 weeks/1 year)

This conversion factors simplify to a simple little equation: y =0.0312(q/u), where y is the number of elephants per year.

Let's try our model using U.S. national automobile averages.
q = 231 miles/week, u =23 MPG


y=0.0312(q/u) = 0.0312(231/23) = 0.31 elephants/year

So it turns out Americans have almost a third of an elephant of stuff popping out of their exhaust pipes every year on average. Want to calculate your own car's elephants quickly? Use my Elephant Tailpipe Calculator!
Elephant Tailpipe Calculator 1.0