A turbine is quite efficient at a steady rpm. When you have to change the throttle setting a lot, like going up and down slight grades, it becomes much less efficient.

We haul engines for Northwest Airlines. One of their requirements to hauling an engine is that you cannot drive with chains installed or over “washboard” snowpack. Their concern is for the bearings in the engine. While operating, the turbine may have very little vibration, but it can’t withstand the same amount that a ICE can either.

With the new focus on “hybrid” technology, their may be a place for turbines there. A turbine that runs at a constant speed coupled to batteries to an electric motor to your drivetrain may be feasable.

Another area that may have some merit is in the APU market. Again, as a hybrid, or as straight power generation. Neither of which would require changing the running speed much.