That’s fair I guess, I would start by checking for a car fax for oil change interval since clean does not mean well maintained. If the car is city driven and oil never gets to temp sludge can build up in the valvetronic system. I personally have replaced the full valve tonic system on n55s n20s b58 as they suffer from the exact same issue. Next I would check for is steering rack clunk f30s have this odd issue where the steering rack would clunk when turning in tight corners or stand still and need a new steering rack with a revised tensioner. Other wise b58 is a great engine nothing really is a red flags. Valve cover can leak and the pcv can fail but those things are very easily fixed and generally don’t cause permeable damage. When you get into the exterior try moving around in your seat to hear for noises since these cars when parked in the sun for long time gets interior clunks.

Have you driven a manual 340i ? The manual version is really just meh, this car really pairs well with the 8 speed. If you really like the manual feel I’d look into like a e9x m3 with the manual.