As it's been mentioned before, make sure she puts it in "D" and not "S". Since I got my Insight my wife has been driving the HCH and she has a problem of putting it in "S", she just won't fess up to it but it's the logical explaination with the exception she waits about a week to pull into traffic waiting for an opening while I'll pull into traffic and accelerate briskly. The speed limit is 55 but EVERYONE seems to do 70+.
That's a thought though. My optimum speed has been 49-50 miles per hour, that seemed to be the sweet spot for my car driving in my area late at night without A/C on and no traffic.