+1 to all of the above.
The only caveat is that it depend on the overall condition of your car: if it has severe corrosion, or multiple major mechanical issues, then at some point you may need to be hard-headed. And also how much you've bonded with the car: if it's just a car, that's one thing, but if it's a car you really like, there's more incentive to keep it alive.
I recently swapped my V40 for a Toyota Avensis. The reason was that the V40 had several problems looming, which would have been uneconomic to have repaired professionally and I simply hadn't time to do it DIY. It pained me not to fix it, for the reasons stated in previous posts, but circumstances were what they were. As it turns out, I like the Avensis more than the V40: it has all the V40's qualities, and it's more spacious and is an automatic (which I'd been thinking of trying). And both Toyota and Volvo have a reputation for making reliable, well-built cars capable of long service lives.
My 740 is another matter. I've spent several times what I paid for it on spares and repairs, and plan to keep it indefinitely - 'cos I've bonded with it!
