This letter references a May 5 Daily Press article and subsequent Last Work comments about using propane fuel for school buses.
The overall lifetime ownership cost — acquisition, maintenance and operating cost — is a better comparison between the two fuels. The "cost per gallon" comparison between propane and diesel doesn't make any sense unless the "miles per gallon" of each fuel is the same. The proper comparison is the "cost per mile" for each fuel. For example, if diesel gets twice the MPG as propane then the propane cost advantage has disappeared. And vice versa. The number of quarts per oil change is a valid comparison if the oil change intervals are the same.
Does the propane powered bus have the same acquisition cost as a diesel powered bus? What is the cost of installing propane fueling and maintenance/repair facilities to replace the existing similar diesel facilities? And don't forget we taxpayers are ultimately paying for the 36-cent federal propane rebate. Overall it does appear to be a good move for a cleaner environment.