Using conservative estimates of how much I might use a motorcycle, unless my calculations are off...

Truck Only Miles Per Year 17,000 Months 12 Miles Per Month 1,417 Miles Per Gallon 13 Gallons Per Month 109 Price Per Gallon 2.35 Monthly Cost $256.00 Total Cost $256.00	30% Cycle Truck Cycle Miles Per Year 11,900 5,100 Months 12 12 Miles Per Month 991 425 Miles Per Gallon 13 55 Gallons Per Month 76 7.7 Price Per Gallon 2.35 2.35 Monthly Cost $179.00 18.16 Total Cost $197.42
This represents a savings of roughly $60.00. That's sixty dollars that isn't going to the dirty bastards at BP/Amaco/Sunoco/Speedway/Clark/etc. Using a bit more optimistic calculations of how much use I might get out of a motorcycle...
50% Cycle Truck Cycle Miles Per Year 8,500 8,500 Months 12 12 Miles Per Month 708 708 Miles Per Gallon 13 55 Gallons Per Month 54.49 12.88 Price Per Gallon 2.35 2.35 Monthly Cost $128.04 $30.27 Total Cost $158.31

This would be a savings of about $98.00. And, as the price of gas rises as it is sure to do, my savings continue to grow. Given all that, I've decided to buy a motorcycle. It will almost pay for itself.