Personally I think you should make a big thing about its mileage which will attract a lot of people and a 2.2 six cylinder is hardly a let down. Z4s are not really a car sold on its performance unless of course you opt for the M. I have seen many 3litres on here for sale newer than yours with well over 100k mileage kidding everyone they drive like a new car. I bet the dealer is itching to get hold of your low miler so sell privately. Incidentally I have the 2.5 SE when I really wanted a 3 litre but with all those high milers no thank you. I have no regrets about my decision as its a keeper so low mileage every time.
I managed to get a little more off the screen price of the new E89 and the car was delivered to me from the garage in Basingstoke Thursday last week, I have been cleaning and tidying over the last few days and I am really pleased with it
I will start a new thread with some details of the car and of course some pictures to show her off.
Thank you again for your advice on what I should do in this situation it helped me with my decision.