Halsey & White (2012) Comparative energetics of mammalian locomotion: Humans are not different. Journal of Human Evolution 63:718–722
This paper presents a comparison of the metabolic cost of walking and running in humans, Australopithecus and other mammals. They use a parameter NCOT (net cost of transport), whose units are ml O2 consumed m-1. The inverse of this parameter would be related to your metres per calorie.
The authors quote an NCOT of 12.77 ml O2 m-1 for a walking human. Using a value of 4 kcal g-1 for glucose, I calculate that this NCOT is equivalent to 14.6 m kcal-1.
Here I found an energy consumption value of 5.8 kcal min-1 (for a 73 kg man) walking at 6.4 km h-1, which translates to 18.5 m kcal-1.
Incidentally, according to the authors of the paper:
The predicted net cost of transport (NCOT, ml O2 m−1) of mammals is related to mass (M, kg) according to 0.54M0.70.