Wow, your numbers are much worse than mine, and I love to drive. I feel for you. Good that you've identified how much you'd gain by changing some stuff around.
For what it's worth, on a 15-year-old car:
- Gas: $3k (around $1k, plus or minus, for work - the rest for pleasure)
- Maintenance: $2k (aggravated by age, relative scarcity of some parts, high labor costs, and my aggressive maintenance schedule to get the car to survive multi-thousand mile road trips every so often, and of course the way I drive it and the ridiculous places where I drive it - off road, snow, whatever - shit tends to break a bit)
- Insurance: $700
- Depreciation: none (good condition old car, pretty much troughed the depreciation curve, and of course it's entirely paid for)
Total: $6k or so, at least half of which is entirely voluntary if not more
In exchange, I go hiking or exploring or photographing pretty much every weekend, plus five to ten thousand road trip miles to see the country.
Assuming that I would be content to not go anywhere far, or be able to bum rides all the time, if I managed to get rid of that $6k a year, I would save about 10% more than I do currently. With your math, that would be "equivalent" to about 10% of a mortgage or less, where I live.
Assuming that I would not be content to never be able to go places, I would probably make up a decent amount of the cost through renting and flying. I figure that would result in saving about 6-7% more than I do currently, and be about 6-7% of a mortgage, in exchange for the freedom a car gets me for all of those years. It's funny how some people get freedom with a car, and others freedom by not having one. So it goes.
Now, if getting rid of a car would cover the entire price of a house (or a very large chunk of it), my feelings on the subject would be very different...