The OP was not about the wisdom of buying old vs new. It was merely an observation about the depreciation of a certain car.
To answer your other questions, I have owned quite a few cars and all have gone well beyond 100k miles. My Omega is currently at 142k miles and 75 CDT at 151k miles.
To address the OP's point in more detail, most cars end up at a value around 30% of their new price at 7-8 years of age and 12k per-annum mileage. So, £6k for a 100k mile DS that cost circa £20k when new 7 years ago seems about right.
My approach is certainly not indicative of a "throw away" mentality. In fact, quite the opposite. As an example, my next car purchase will be a 8-10 year old CLS. The £50k car will cost me £10k with circa 70k miles and FSH. I will spend £5k over a short timeframe replacing all the parts that wear or tire with age and would otherwise most likely require replacement during the following 7-8 years of ownership. I will therefore end up driving a £50k car, which will drive as if I had bought it new new, for 8+ years and an initial outlay of £15k as opposed to circa £40k depreciation over the same period. This is value for money in my book.
This approach has worked for me every time and is the reason that you will not find any posts from myself about things having gone wrong with my 75's or my Omega. The latter will be 20 years old in September.
Take a look at my "Preventative Maintenance" thread that is the focus of my 75 CDT and see my approach in action.
I do not throw anything away until there is absolutely no choice - I am an Indian and an Indian can make things last longer than most!
