If you want to do this comparison please do it right: The Diesel equivalent to the Golf GTI is the Golf GTD. There's more than just displacement that makes up an engine and the fact that is some kind of turbocharger.
Their difference in 0-60 seems to be 6.4s vs 7.4s according to what I find. Guess the difference in higher regions might be even less, because of a different torque profile in turbocharged diesel engines.
The GTD is Euro-only, so it's harder to get performance comparisons. But it's still much slower than the GTI, I found a 15.6@93 in the quarter.
0-60 is an awful way to measure acceleration; most of what it measures in modern cars is traction, since a Mk7 GTI will shred the front tires with a hard launch. So high five second and low six second times are both accurate, it just depends how good the launch was.
That's why you compare quarter mile times when looking at acceleration. And the GTI is still so much faster than the GTD; a full second and a half and 7mph trap. Meaning, in a drag race, the GTD wouldn't be close enough to read the GTI's license plate.
Their difference in 0-60 seems to be 6.4s vs 7.4s according to what I find. Guess the difference in higher regions might be even less, because of a different torque profile in turbocharged diesel engines.