**Efficiency of Biking vs Driving**

According to random places around the internet:**Cycling is about 31 Calories/Km** (for a pretty average person)

To compare this to driving we need to do a little more leg work:

First we need the Caloric value of gas (we'll figure it out for a Liter of gas):

((MJ/Kg of gas) * (convert to Jules) * Kg per Liter of gas) / (J in a Calorie) = Calories/Liters of gas

(44.374 * 1000000 * .703) / 4184 = 7455.76 C/L of gas

Now we take this number and plug it in to the efficiency of a car:

Efficient car (40mpg) in Km/L : 17.01 km/L

(Calories in a Liter of gas) / (Km/L of an efficient car =

7455.76 / 17.01 = **438.31 Calories/Km for an efficient car**

Therefore with these rough numbers Biking is around 14x more efficient then driving. And yes I know measuring gas in calories doesn't really make much sense... but it does help when making this sort of comparison.

Interesting side notes:

- You burn about a McDonald's double cheeseburger of calories every Km you drive.

- You burn around half an apple of calories ever Km you bike.

Where I got my numbers:

- Calories in a big mac: http://caloriecount.about.com/calories-big-mac-i21111

- MJ/Kg of gas: http://stason.org/TULARC/vehicles/gasoline-faq/4-9-What-energy-is-released-when-gasoline-is-burned.html

- Liters in a Kg for gas: http://www.triplepundit.com/pages/askpablo-tailpipe.php

- Calories/Km of for biking: http://www.stevenscreek.com/goodies/calories.shtml

- Calories in a Cheese burger: http://caloriecount.about.com/calories-mcdonalds-double-cheeseburger-i53968

- Calories in an Apple: http://caloriecount.about.com/calories-apples-i9003

*These calculations brought to you by the back of a napkin*