I have had my '13 MKZ Hybrid about 3 weeks now (took delivery on 20 June 2013) and I am very happy with my car's acceleration although I must acknowledge that I've never been a lead-footed driver. So far, I've not had reason to "floor it" due to some dangerous situation. Given that I have only a little more than 1000 miles on my new car, I'm trying to baby the engine a bit during the first couple thousand miles.
However, relatively soon, I'll be going on vacation, putting 1000+ miles on it within a week, so I'm anxious to see what my mileage will be like and presumably at some point during that time I'll have need to accelerate very quickly.
I have read that you'll get more pep from the gasoline engine if you use premium fuel. For that reason, in the very few fill-ups I've done so far, I've put 91 octane in it. I'm not sure if I will continue to use 91 octane but probably will during the upcoming vacation road trip. Later, as I settle in to mostly in-town driving, I may back off to "regular" or 87 octane (or maybe "mid-grade" or 89 octane).