With current technology road cars do not use gas turbine hybrids because of price, reliability, fuel economy, and not meeting the customers needs.
All of these problems will be fixed in the near future.
Price: It is possible to 3d-print the engine in titanium and this has already been achieved. Expect turbine prices to drop.
Reliability: With air bearings, and a good filter this should not be a problem
Fuel economy: A turbine in ideal circumstances will be more economical than a piston engine.
Customers needs: Old turbine car s drove with gearing , and were not responsive to the throttle. Future turbine cars will be hybrids using a gas turbine running at optimum speed to drive a generator , charging a super capacitor or battery which then powers electric motors. For short journeys the turbine would not be needed and battery power would be sufficient.
I would like to see Formula 1 car racing, using turbines to help push the technology. To set a standard some teams could use V12 piston engines, so we get the sound craved by the spectators, whilst the big car companies are developing the turbines which will eventually power their road cars. Each year allowed fuel would be reduced to encourage economy (while still having to beat the V12 cars). Ideally we could have teams running one or more of each type of car.
Edited by scolbourne, 30 January 2018 - 00:01.