I've never driven a 3 series, but I have had a 5 series before that I loved. I think that you will like the 7 series much better. I have one now. I can't give you any tips. I have had it only about 6 months. Maybe while braking you can see if there is any vibration. I didn't notice it on mine at first, but now I think that I will need to replace the rotors soon. Hopefully, they kept good maintenance records, but I don't and I take good care of my cars, so just look, look, look at everything. The 7 series is very comfortable on trips. The drivers seat adjusts to about every position you would want. The drive is very smooth. I have a six cylinder and have plenty of power even for the car's size. It is a roomy car, but doesn't look like an elephant on the road and certainly doesn't drive like one. Look to see if the took kit is still intact. Just because the person who originally bought the car had a lot of cash doesn't mean he or she takes good care of things. Good luck.