Our Truck Passes 300,000 Miles

This truck is 12 years old and it has spent all of its life traveling from the farm to the Bay Area. As Molly delivers the boxes today the odometer will pass 300,000 miles. It is still going strong but we do have to think about a replacement. One issue we have is that this truck has been running on straight vegetable oil since 185,000 miles and the newer trucks have computers which do not understand this. It is possible to reprogram the on board computers of the newer trucks but not easy and not cheap. We would like to continue using the vegetable oil as it is cheap, is carbon neutral and has only 50% of the emissions of diesel.
If I could have what I wanted it would be a hybrid diesel that can run on vegetable oil. I believe that FEDEX has 50 diesel hybrid deliver trucks that they are evaluating. I understand that the technology is very viable and only hope that sense will prevail and some one will make them available to all and sundry.