The trouble is, those online valuations by AT or insurance sites etc. are often wildly inaccurate on older cars, especially ones where the low mileage carries a huge premium. They do not in anyway reflect the true amount that such a car may command and sell for.
Over the last 43 years, I have personally owned over 70 BMWs and probably near as many Mercedes. I am really not exaggerating when, in the past, I have literally sold older, classic BMWs for up to TENS TIMES what some online valuations would suggest.
Just two days ago, I had to renew the insurance on my Mercedes SL. It’s a car that I almost never drive, so my main priority was getting a cheap premium. When woman the on the phone at the insurance brokers was going through the details it came up with a valuation at least 3x less than it is really worth!
Of course, this made the premium much cheaper, so I just kept my mouth shout! And, it’s only significant if I was unfortunate to have a complete write-off in car. (Not impossible but unlikely, as I only drove it less than 100 miles last year)
To get a better idea of the real value, it’s more accurate to look and compare the adverts of as many cars of the same model as possible and then make individual adjustments for the car in question based on factors such as mileage, condition, history, specifications etc.
For a relatively common car, like a Z4, that is relatively easy to do.
The 23i that you are looking at is with a dealer that sells quite a few Z4s. It is a perfect case in point!
It’s £12K price tag is firmly based on the facts of its very low mileage and single ownership. This commands a huge premium. This is a reality. Whatever, people say that “low mileage isn’t always “better” maybe sometimes be true….but the market doesn’t see it that way! It essentially over-ride many other considerations….and the effect is not linear!