A 155-lb. person biking with moderate effort (12-14mph) burns about 563 calories an hour. Source.
I'm rounding the distance down to 10.18 miles an hour to account for stop signs and traffic lights.
The average car gets 20.36 mpg.
So, conveniently, it takes a cyclist 2 hours to go the distance that a car would go on a gallon of gas. The cyclist will thus need 2 x 563 = 1126 calories to do so.
What is the cost of 1126 calories? Of course it depends on the food:
Food fuel cost compared to cost of a gallon of gas
$2.88 ground beef (85% lean)
$2.83 chicken breasts (boneless)
$9.53 salmon or catfish (farmed)
$2.01 milk (2%)
$6.67 Big Mac
$0.71 pinto beans
$0.69 rice (white)
$1.21 rice (brown)
So that lets us compare the price of bicycle energy with the cost of gas.
We can also do a similar calculation: If we spent the same amount of money on gas that we spent on food, how far could we ride the bicycle? That is, what is the MPG of biking, if we spend the same amount on food fuel that we would have spent on gas fuel?
The average price of U.S. gas is $3.72/gallon. We can go 20.36 miles on $3.72 in the average car, how far can we go on $3.72 with a bike?
Bicycle MPG (cost of food vs. cost of gas)
026 miles - beef
027 miles - chicken
008 miles - fish (salmon)
026 miles - eggs
038 miles - milk
025 miles - cheese
011 miles - Big Mac
106 miles - pinto beans
109 miles - rice, white
063 miles - rice, brown
082 miles - oats
048 miles - potatoes
037 miles - Cheerios