So I took the car to the dealer, drove around with a technician and he noticed the lag/surge as well. They're going to reset the memory the car had taken on from the previous driver, and they're hoping that reset will help with the issue. Basically un-learn what it had learned from the first owner. I'm not holding out much hope. Will get the car back tomorrow and report.
Hoping they'll also update to the latest 240E software, but they seemed a bit reluctant to do that. Not sure why they don't like to do that.