I owned the 2015 pictured above from around 17,000 miles to roughly 31,000 miles. The only troubles I had with it during that time was a slight gear oil leak around at one of the front axle outputs, one of the electronically controlled dampers leaking and all of the shock boots degrading to dust. I had the same output seal leak on my i3, which used essentially the same drive train, and the boots appear to be a common problem on BMWs of that vintage.
Oh, I did have one of the brake bleeder nipples for a front caliper back off while tracking the car at Road America. That was my fault though.
The car was always a occasion to drive-- looked awesome inside and out. It always felt like the future, though maybe it was the future circa 2010. Performance, while not Tesla Plaid level, was effortlessly available to well in excess of the legal limits. In sport mode, it would make awesome noises, during full throttle redline upshifts. That those noises mostly played through the interior speakers didn't make them sound any less awesome.
The interior itself is very comfortable for the front seat passengers, but the back seats are only suitable for decapitated double amputees. Ease of entry isn't as bad as made out to be on the internet, as you're working with gravity. Exit up and out across the very wide sill isn't something you're going to get done gracefully. I damn near ruined myself hopping in and out of the driver's seat past a cabled up OBD connection while trying to do a computer assisted solo brake bleed at all four corners.
Cargo area in the rear is the size/shape of something like a couple of cases of beer, and gets pretty warm.
The gas struts for the doors are consumables-- need to be replaced every 2-3 years. Easy DIY and the parts are a couple of hundred dollars. The plastic plunger assembly that pops the rear hatch also tends to crack/break, and can leave you unable to open the hatch. Also an easy DIY replacement, and I recall the parts being less than $50.
I found parts support to be very good-- as it's pre-2019, all of the parts information is available at www.realoem.com. I've also saved a lot of tech and service information I downloaded, and I can share if you contact me via PM.
Periodic maintenance like air filter, spark plugs, oil, oil filter, brakes are quite straightforward, though the reach to the engine bay is a little long. You can probably pick up an oil filter (and the corresponding wrench) at a BMW motorcycle service center!
I never got around to doing a coolant change. The internet says it's impossible, but it's pretty clearly laid out in the service information as requiring a vacuum filling tool.
Service procedures are available for download at a cost of $30/24 hr from BMW. If you're ambitious, that access even allows you to download the ISTA computer service tool, though bootleg versions are available as well.
If you need dealer service/support, that can be more problematic-- the closest dealer that would touch it was 2 hours away. It's kind of like trying to find a dealer that will support one of the V-10 M cars.
What ended up as one of the bigger deals to me though is that the tire choice on the OEM wheels is extremely limited. Some pretty odd sizes-- 215/45 R20 in front and 245/40 R20 in the rear. At the time, you had the choice of the OEM Bridgestones, which were always out of stock, or Pirellis. Both were summer only tires, and the Pirellis weren't even supposed to be stored below 37 degrees F. It looks like you can get Michelins now though-- while I owned the car, you could get the rear size, but would have to import the fronts. None of the options are inexpensive. I think there's a wider choice available in snow tires.
I'll admit I was always a bit fearful I'd run into some kind of maintenance issue, but I definitely miss the driving experience and the attention it would get. It should also be noted that collision coverage on a carbon fiber car runs kind of high. Depending on your state, plates for a car with an MSRP of nearly $150K can also be rather dear.
In the end, I traded it for a 2022 Supra as being better suited for occasional track days. In the weird 2022 auto market, the trade in value was nearly what I paid for it when purchased as a CPO.
