maybe describe what his intended use are, then it is easier for us to help you.
- if he is into 2 seater with light/nimble handling, cayman s is a very good choice. but i feel it is a waste if he doesn't track his car.
- if he want a more comfy car with some sportyness for street use, then e93 m3. nothing beat a hard top vert in daily driving experience especially that v8 sound. it has enough room for 4, fit all his golf bags and adult toys, and it has presence.
- Or a based panamera if he have the bucks for it. I think it suites your dad age very well.
- if he like none above, then S5. it is safe, very comfy, and look very business like. a black one would do the trick IMO. don't get the s5 vert though cause I think the soft top ruined the whole look of the car.
one thing I noticed is insurance for the cayman s is way more than the m3 for some reason, atleast in my area. I did a quote for both and the cayman s was atleast 70 bucks more than the m3 a month. That's more than a c6 z06 and almost the same as insurance for a gt3. I don't quite get that.