I've driven a 535d regularly and owned a 530d until recently, and there is a clear discernible difference, largely due to power delivery as previously mentioned. In addition at higher speeds, the greater power of the 35d comes in handy. However, the 30d engine was the smoother of the two and definitely more relaxed in town. Having said all that I am now in a 335i, and it is by far the most fun of the three. Good luck choosing
