Be careful with family weekend fun cars. I thought the same and lost a lot of money in the process.
If you get rid of the GT4, get the 991.2 Turbo S, otherwise you will miss a Porsche in your garage.
If this is not the car you have in mind, get a RS6 Performance but I have to warn you, you are going to miss a sportscar along the way.
Alternative: Get a BMW M3. Four doors, enough room for a small family, pretty inexpensive. Keep the GT4.
Or get a RS3 as a family car...or a RSQ3 Performance and keep the GT4.
From my (sad and costly) experience, there is no car to fit all your needs at the same time.
If you get rid of the GT4, get the 991.2 Turbo S (maybe even as a cab because it sound better with open top). Or get the Turbo (without S) as a cab, this could be cheaper and the performance difference is not that big.
I know it isn't easy. When my first kid arrived, I wanted to change everything but trust me, it is healthy to be a little bit egoistic and to still enjoy yourself from time to time and you are a car guy, like I am, so be careful what you choose.
Oh, before I forget it: Mercedes puts a E63 S Coupe 4matic on the road sometimes next year or so as far as I heard. Smaller than the S class (and probably sportier) but bigger than the C class and with AWD.
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RC (Germany) - Rennteam Editor Porsche 991 Carrera 4 GTS Cabriolet, Porsche Macan Turbo, Audi R8 V10 Plus (2017), Mini JCW (2015), Jeep Grand Cherokee SRT (2014)