The incremental cost of a pound of fuel is a rounding error in shipping. You might factor it in, but it'd be very far down the list of priorities. Interestingl

The incremental cost of a pound of fuel is a rounding error in shipping. You might factor it in, but it'd be very far down the list of priorities. Interestingly, cars have similar economics. Details vary quite a bit, but every 100lb (nearly two full tanks of gas for me) makes you 1% less efficient. It only really matters if you have driving habits that tend to burn that excess energy somewhere, like rolling in hot to a stop light and hitting your brakes rather than anticipating the light cycle and coasting in.