It's actually refreshing to hear other people share sentiments. Since your in Cali you should visit tc Kline and get some goodies for your car after you put some mileage on it
I love the z4 coupe but like you I needed a backseat (just in case) and because I drive a lot and already have a toy (rx7 turbo) I went na and didn't regret it one bit. My only complaint is the lack of LSD. I want an os giken mechanical unit with a 3.9 final. That'll really pep the car up.