...approximately 2/3rds of our offers are C Loads, and in fact the offers we receive on C Loads are higher, than those for the D Loads (which require the heavier duty truck).
This simply doesn't make sense to me. Has anyone else noticed the difference? What are your strategies for bringing D Load offers in line with expenses? What do you consider a reasonable cost/mile?
Keep in mind that it is expedited, exclusive-use freight you are talking about. Shippers ask for our trucks not so much for their weight carrying capacity as for the door-to-door, straight-through services we provide, and the professionalism with which expediters provide it. Even with D loads on a D-unit, the truck is rarely full.
It's not about the weight or space. It's about expedite. Shippers can save a lot of money by using non-expedite carriers to match their goods to truck size and capacity. They use expedite carriers because they need expedite services.
We have driven D and C trucks. It makes no difference how many pieces or how much weight or how much space is required for a load. As long as it fits on our truck and the load pay is profitable, we take the load.
Regarding your cost per mile question, you probably noticed that no one answered it. That is partly because people are afraid of the ridicule or severe criticism they would receive here in the open forum if they put their number out. It is also because there are so many variables between trucks and drivers that feed into the cpm number.
It is best for you to develop, as best you can in a fleet truck, your own sense of your own cost per mile. Keeping a spreadsheet is a good start.
Finally, using a spreadsheet to track your pickup and delivery locations is also a good thing. When you attended FedEx Custom Critical orientation, did you receive one of those black books? That run journal is a good resource. We write each run into it and later transfer the data into a spreadsheet. Running zip code sorts is an easy way to determine what our good express centers are and the better locations within them.
Finally, finally, I agree with the advice to stick with a D-unit if you are driving surface expedite freight. Other than sleeper space, there is little to be gained by running a C-unit dry box, but there are D-loads to lose.