Emission of diesel is still higher than gasoline in NOX and PM. Even in hybrid it is still a higher emission one, plus it is much harder to keep a diesel engine hot with the way hybrid works by shutting off the engine as need. If you have a mild hybrid and just use electric motor for eCVT and acceleration, it may work for bigger vehicles with a small diesel, but small car diesel hybrid can be keeping it cold too often, literally like running diesel in the winter cold start problem.A hybrid TDI is the best of everything. None of the reasons we cant have them are valid it is just a bunch of hogwash.