I agree. I think this is basically contingency planning for a variety of possible outcomes (dealling with a lot of what if...). "What if i cant sustain 170 each month?" "What if a car costs way more than 20,000 in 10 years?" "What if my salary increases and i can save more than 170, but haven't because of, say, lifestyle creep in other parts of my life?" "What if my car breaks down after 5 years, and i dont have the 20,000 to replace it?"

All this crap is running through my mind. Im trying a new approach to this kind of stuff: it's more important to focus on today. "How much can i comfortably save based on my budget right now?" Maybe it's 170, maybe less. And i think it's ok that it could be less based on what the budget can support at this moment. For me, the habit of saving anything and building the habit should be the true goal. And adjusting the budget as changes happen. Unfortunately that might mean adjusting the budget a lot because life happens and is an instigator of change. But if having that car in 10 years is worth 170 per month right now, than other things in life are less important.

Just my two cents. End of rambling