Turbines have great power to weight ratios but very poor efficiency at low loads (cruising on the highway is a low load). GM actually seriously considered this along with Chrysler and it was abandoned due to the oil crises.
> General Motors at one time manufactured a bus powered by a gas turbine, but due to rise of crude oil prices in the 1970s this concept was abandoned. Rover, Chrysler, and Toyota also built prototypes of turbine powered cars, Chrysler building a short prototype series of them for real-world evaluation. Driving comfort was good, but overall economy lacked due to reasons mentioned above.
> General Motors at one time manufactured a bus powered by a gas turbine, but due to rise of crude oil prices in the 1970s this concept was abandoned. Rover, Chrysler, and Toyota also built prototypes of turbine powered cars, Chrysler building a short prototype series of them for real-world evaluation. Driving comfort was good, but overall economy lacked due to reasons mentioned above.
https://en.wikipedia.org/wiki/Engine_efficiency