V40 Performance (Long Question I'm afraid)

I had something similar, but it was the handbrake mechanism had failed on one of my rear calipers resulting in the pads not being tracted fully. But you'd know if that was the case as it tends to smell a bit and it gets mighty hot :-)

The GDI isn't the world's fastest off the blocks. i've had cars that were happy to pulll away in second but the 40 isn't happy if asked to do that. is your tick over ok? you may be coked up ( see other GDI posts) when ine was decoked it made the heck of a difference!

I agree with David, it may be coked up, as these are prone for it. Try a fuel treatment like Redex etc and a good thrashing (seriously), oh...and try a search for GDI in the search bar, there's loads of similar problems/info to be had. Let us all know how you get on too.