So is this thing.
I would love a diesel / electric hybrid 1-ton pickup.
Unfortunately, such a thing cannot be made (or can easliy be modified not) to abide by the speed limits.
Consequently, it will never happen.
But General Electric and EMD have developed Hybrid's that have banks of batteries in them that Store the electrical power into them.. then are applied to the traction motors as the engineer directs.
But this is all new stuff.. and I only have heard of the BNSF Railway experimenting with one or two switchers with this technology.