It's not about reducing greenhouse gases.
porsche engnineers built a car 130 kg heavier but 160 bhp stronger.which means on the one hand more weight but also much more power when its needed(acceleration etc)
meaning: 480 bhp (engine)+ 160 bhp (hybrid) = 640 bhp thats like a lamborghini!
well you don't have this power all the time but to me it's a good step to combine two different types of technology!
(VIDEO IS A LITTLE BOXED BUT BETTER MUSIC WITH THIS ONE)

Porsche has just unveiled its 911 GT3 R Hybrid, a 480 horsepower track vehicle ready to rock the 24-hour Nurburgring race this May. Porsche's latest supercar will use the same 911 production platform available to consumers today, with a few race-ready features including front-wheel hybrid drive and an innovative flywheel system that stores kinetic energy from braking and then uses it to provide a 160 horsepower burst of speed. The setup is sure to offer an advantage when powering out of turns and passing by other racers.