Why not a turbine powered hybrid car similar to an aircraft APU?

Question

Ok so with all of the inefficiencies of the reciprocating internal combustion engine why don’t they make a hybrid car powered by a small centrifugal turbine that would work like an aircraft APU. The car would have an all electric drive system and the turbine would produce electricity for the electric motor. The FADEC computer would control fuel flow to the turbine as more power was needed. Trains have been doing this for decades so why not cars? A plus would be that you could use any liquid or flammable gas for fuel.

Answer 1

Size, weight, expense?

Are hybrid cars really the way forward? On this side of the pond we are generally going for small cars, the power to weight ratio enabling small petrol injection engines

If you're into alternative engines, try googling stirng engines, they are appropriate for cars, and serious work has been done.

Answer 2

Because any sort of gas turbine makes a 1967 Cadillac look like a mileage champion.  They have horrid efficiency, and even intensive engineering hasn't helped as much as everyone had hoped.  They'll give you a lot of power in a very small package, but you pay for this in lousy gas mileage.  

Moreover, turbines like to go at very high speeds, which is why there's always a heavy, expensive gearbox associated with them for any but flight-propulsion applications.

Answer 3

Typically, aircraft APUs run at 15% efficiency.  A piston internal combustion engine is around 30%.  However, a fuel-cell based APU shows more promise.  See references below.

Answer 4

because the automobile companies control the politicians who control government policies.