I was debating wether to get a 335i/135i or Z4. Test drove all of them and after driving the Z4 I had no doubts which one to get. The seating position for me had the biggest impact. 335i/135i felt just like normal cars and Z4 feels much more special in my opinion. You are sitting very low on a rear axle with a long hood in front of you. Makes me smile everytime I drive it