How old is too old for a car

My beloved Volkswagen Passat just completed her 14.5 years of life with me and has been a great and very reliable car to drive around. Now with 140K+ miles on the car there is always the thought that lurks in my brain, how many more days with the same old car? the question became even more relevant couple of months ago when the mechanic told me that the solution to fix a check engine light would cost $1000 to fix (it ended up being ~$1600) to fix. Can I not keep the money and dump the VW and buy a different one? my mind said may be but my heart said vehemently no. 

My problem was 2 fold, I need to spend the money to fix the check engine light on the car or else whoever willing to buy the car would negotiate the price of the car as though it would be sold for parts. Secondly, since I am already paying for a car loan I didn’t want to add one more car payment (if I can avoid it). I guess this is the first time in the 14 years I have owned the car I did a compilation of how much I have spent over the years (last 5-6) in maintaining/up keeping the car, turned out in the last 6 years on an average I have spent $1,200/year on maintenance including brakes, tires and battery. So, technically the costs were in favor of keeping the car.   

I pretty much discussed with every one I can think of about the car (to fix it or not to) and I think the best answer came from a colleague of mine. Its not the money spent alone but also the time the car needs to spend in the mechanic shop and the inconvenience it would cause and how much of it can you bear and endure, there are advantages of keeping the old car for you don’t have to worry about car payments and if the car is sufficiently old enough you can save on the insurance too and in the end if you can find a good mechanic you can trust and bear with the car’s absence for a few days in a year then longer you keep the better off you are financially.

After going through 3 different mechanics in last 7 or so years, I think I have found a good mechanic in Brink Motorsports and true to their ratings on all websites (Google, Yelp etc), I recommend them in a heart beat for VW/Audi repairs.

Yes I did make my car street legal and have to decided to run it for another 2 to 3 years or longer if possible :).