Only a couple things tie me to the car -
We looked for it for a long time (e46 5 speed wagons are rare), and it's the car I wanted.
It serves our needs well. It's got low mileage (much lower than a $5000 Toyota), and it doesn't cost much more to operate than a cheaper ride.
I don't really feel like dealing with buying/selling.
By the time it's "used up" - in 8 years or so, it'll still worth $4-5k and we'll have something like $10k in the car replacement fund.
It just seems to me that controlling recurring expenses is more important than long-term expenses. I know that with cars MMM recommends buying for price, reliability and economy. This car is decent for the second two, and factored over 10 years the difference between $14k and $5k is only $75/month, less than most people spend on their lunch.
edit - one other thing I like about the car - when we were shopping we were looking at subarus, mazda 3s and maybe a newer honda fit, but subarus and mazdas of a similar vintage go for about the same as we paid for the bmw... they have great resale, bmws have shitty resale. "Oh, it's the cost of maintenance" Only kind of, the cost of maintenance on some "luxury" vehicles is greatly overstated. My folks spend more on that Subarus than we do on our bmw (love those boxer headgaskets, yeah?)