// car-interface.h ///////////////////////////////////////////////////////

class CarInterface
{
public:
    virtual void drive() = 0;
}

// car-impl.h ///////////////////////////////////////////////////////

#include "car-interface.h"
#include "car-export.h"

#include <memory>

class CarImpl : public CarInterface
{
public:
    void drive() final;
}

extern "C" CAR_EXPORT CarInterface* createCarImpl();
extern "C" CAR_EXPORT void releaseCarImpl(CarInterface* car);

using CarPtr = std::unique_ptr<CarInterface, decltype(&releaseCarImpl)>;

inline decltype(auto) createCar()
{
    return CarPtr(createCarImpl(), releaseCarImpl);
};

// car-impl.cpp ///////////////////////////////////////////////////////
#include "car-impl.h"

void CarImpl::drive()
{
    // driving stuff
}

CarInterface* createCarImpl()
{
    return new CarImpl();
}

void releaseCarImpl(CarInterface* car)
{
    delete car;
}

// main.cpp ////////////////////////////////////////////////////////////

int main()
{
CarPtr car = createCar();

car->drive();
}