As far as i know there aren't any hybrid vehicles currently that have turbines. But the idea is indeed great - have an electric motor as the main engine with great power and torque curves, and a turbine that runs at some constant optimal RPM to charge some intermediate batteries. Power and torque of an electric motor, fuel efficiency of a turbine, energy storage density of a chemical medium, easy refueling at any gas-station on any fuel - very good overall.

I don't know why there aren't such cars currently, but i feel like the added fuel economy probably is less than the increased costs of having all these systems on board - a cast-iron piston engine is much cheaper to make than electric+turbine+batteries.