What shipping company is using a gasoline engine requiring spark ignition instead of diesel that ignites under compression?
I know of a couple of smaller shipping companies running on propane for their shipping trucks.
As for diesel, it might still be possible. I am not an engine designer or a mechanic but I do know that much of the catalytic “stuff” is designed to burn off particulates post combustion. Perhaps a high enough powered laser can burn these within the diesel engine before it is exhausted. Not sure that would provide any additional power but it could treat the exhaust. Perhaps enough to remove the catalytic converters and thus regain the power lost to them???
Just wondering out loud here.