Looking at purchasing a 320i with AT for daily driver - differential gearing question

As the title indicates, looking for a DD, primarily for my son to commute to college (5 miles each way) and perhaps some freeway driving on the weekends. I understand that the AT is not geared for the freeway (perhaps stop and go traffic, yes!) as I hear it tachs out around 60-65mph. I believe most AT have the 3.64 ratio diff. Would swapping a 3.91 make a difference? If not, not sure what my other options would be other than a 5spd, as I don't think there is any other diff gear ratio options. TIA

Looking at purchasing a 320i with AT for daily driver - differential gearing question