I can't seem to find any official documentation for that number. I did find it on a couple 3rd party websites, but they also listed the engine as 190hp - 200hp, so I dismissed it as false, however 10:1 does sound far more believable, especially for a high boost turbo engine.The UK brochure quotes the compression ratio as 10:1.
I used the calculator here:
and the official specs located here:
but now that I try to re-do the numbers I think I mis-entered something as I can't get anything meaningful to calculate again (it's saying 2:1 ratio now!), so I believe my conversion to the tools inputs was faulty.