Patriot

The laws of physics are very strict. To climb a hil from point A to point B, it takes the same amount of energy (calories) regardless of how fast you are going. Now if you do it faster, your body may be producing more Work, but that's a differant equation based on efficiency.
So, If you burned 300 calories to go to work at 12mph, you are also burning 300 calories to go to work on the same route going 15mph, because even though you are going faster you are doing it in less time. This is of course, if all other variables are the same, such as total bike and body weight, temperature, wind speed and direction, etc.