Return unique_ptr with abstract class inside

I am trying to encapsulate details of the Engine implementation class. To do that I am returning std::unique_ptr of abstract class (IEngine in my case) instead of Engine. But I could not do that due to the compile error. I could return raw reference and it works but is that possible with unique_ptr? Thanks in advance.

class IEngine
{
public:
    virtual ~IEngine() = default;

    virtual void Start() = 0;
};

class Engine : public IEngine
{
public:
    void Start() override {}
};

class Car
{
    std::unique_ptr<Engine> m_engine;

public:

    std::unique_ptr<IEngine>& Get() { return m_engine; } // Here is compile error
};

int main()
{
    Car lambo;
}