@bombur Hi I will try to help as far as I can and sorry if this is a Granny and eggs post
As with David and Tony I also have the 23i with the 2.5 ltr 6 cylinder carried over from the e85, that I purchased from BMW in 2019 as a 1 owner 50k car, its now done 72k with no non maintenance issues, its quick enough but to get the very best out of it you have to get the revs up, it starts to really come alive post 3500/4000 RPM
If you opt for the 20i or 28i then these are 4 pot 2 ltrs turbo's, I would say the 28i is the one to go for as its higher BHP. I test drove an auto 20i and it was a bit sluggish tbh. Doing some research I concluded some were having turbo issues so I opted to steer clear, but that was my own conclusion and I suspect many 4 pots have been just fine.
If you are into performance tuning then the 23i is not the one as you gain next to nothing, but the 4 pots as I understand can be tuned to much higher BHPs (maybe this is where the turbo issues come from?) The daddy is of course the 35is, but you will need deep pockets for a good one, if you can find one. I dont really have any info on the 3.0 ltrs as I never considered one.
If you are opting for an active suspension car then check the struts, they fail, and some at low mileage. They are I believe somewhere in the region of £1.200 to £1,400 a corner to replace.
As said by others check and then check again several times that the roof is working correctly, no stalls or juddering. Check the boot area for water ingress especially around the battery, (this is where the roof pump and relays are located) earlier cars leaked through the rear lights an issue that was rectified on later cars, the later rear lights can be fitted but are approx £500 each new.
Check all four corners of the roof, some are prone to rust bubbles, my had the start of this but was repaired by BMW under the paint warranty.
The options list on e89s was long, but what owners added is very varied so think about what you want, from my searches for one and others I have seen not many e89s came with everything. Cruise Control is rare as it was a really expensive option, but it can be added, I had it done by a forum member and I believe Tony has too.
As said mine has done 72k and I have wheel bearing issues, I've changed the front and they were definitely on their way, rears next as one is definitely starting to make a slight rumble.
Gearboxes can whine as can diffs, no different to other BMWs, just worth checking, if you hear anything just try to determine if its bad or acceptable, test drive with the roof up as well as down as this will make any issues more obvious.
Air con pump bearings can rumble so that's worth checking.
The larger wheel sizes are very prone to cracking and its a big issue for a lot of owners. If you buy a car with run flats my advice is remove them, they make the ride horrible and many believe add to the wheel cracking issues. I have 17" wheels and they don't seem to be an issue.
To sum up;
Having done many long Euro trips in a Z3M and the e89, for comfort I would go with the e89 every time, hence I still have it and not the M. As for driving experience / pleasure the Z3 is much more fun, the Z4 feels very modern by comparison as is to be expected and not to everyone's taste. I have had no issues with the car to be fair and other than preventative maintenance, servicing and some preference items such as up-rated suspension, exhaust etc the car has been trouble and cost free and has never let me down. (YET)
As with any car service history is more important than mileage, the more electronic gizmos fitted will most likely lead to more future problems. If you can find one at BMW for the right money its worth considering that route as you will get 12 mths full BMW warranty, but you are probably more likely to find a good car privately from an enthusiast owner.
Fuel consumption is good, I drive mine relatively hard on occasions and use as much of the RPMs as I can
and it returns 34 to 36 mpg per tank most fill ups, 30mpg at worst, on a run to Italy and back over the Grand Ballon and Swiss/Italian Alps it returned 42mpg for the whole trip.
As you are not far from me then feel free to come to Zedshed West for a chat.
If you find a car reasonably local I am happy to come along for some support if you think that would be helpful.
Hope this helps
Niall
