The real savings in keeping an old car going are if you skip the labor costs. 1.5 years ago my car's trans began a death spiral....I located a used one with 160k on it through this forum, drove to get it, brought it home and installed it. Total cost of trans, trip, other things I replaced while doing it, about $670. Car was only actually down for about 2.5 days. I work real fast when a major failure occurs. Overnight shipping makes a lot of things possible.

I have since put nearly 30k on the car.....and have not had any additional major repairs at all. Of course at this point I've replaced a vast majority of parts that can fail, so I am fairly immune to sudden failure. I am a firm believer in the maintain it like an aircraft approach. It has worked well for me so far.....I've spent probably 12k on my W126 in the past 7.5 years including purchase price....and its given me over 100k of worry free driving, and more yet to come....I've never been stranded, its never been towed. Not too bad IMHO. Very very very few sub 20k cars would do 100k miles reliably without at least a small li$t of repairs. And even then, the car is still 20k, its a new piece of plastic in comparison, feels cheap, rides cheap, sounds cheap. And along the way, insurance will be considerably more, etc.
Old cars win, they are ALWAYS cheaper as long as you have a decent idea of what you are doing.
Very few people take into account ALL of the price factors of a newer car:
-Still has maintenance
-Can still break
-Much higher insurance
-Higher annual registration
-The depreciation after purchase
I pay about $36 a year to register my W126 and barely $600 to insure it......even a newer C-class would be in the $140-150 range just for registration....an S-class....much much more.
When I see what people spend every month on their stupid SUV's and such, it blows my mind. $400+ for the payment, another $250+ for insurance, maintenance, and another few hundred in gas. What is wrong with people?
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-diesel is not just a fuel, its a way of life-

'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)