Low cost-to-own Family Car

If you only need a rear seat as roomy as that in your current car, few four-door cars are ruled out. I used to have two boosters plus a car seat in a Mazda Protege5.

Since you like to hold onto a car forever, Toyota and Honda tend to be the best candidates. Unfortunately, neither has offered a wagon recently (unless you count the Acura TSX, now discontinued).

A Toyota Prius v might be a good fit. Very good reliability and fuel economy, especially if driven to maximize the latter. Likely inexpensive to insure.

The Honda Fit hatchback might have enough cargo area for you. Worth checking out.

Beyond that, you're looking at a crossover. The new HR-V is essentially a Fit with a higher ride height and optional AWD--no extra space inside. Next size up isthe CR-V and the Toyota RAV4. For 2016 the latter will be offered as a hybrid.

The Mazda CX-5 might also be a good bet. But as with the latest Subarus it's too soon to say how it'll hold up after 10-12 years.

If you're serious about minimizing cost of ownership, in addition to depreciation, I would think especially about opportunity/finance cost and insurance. If you can invest your money at 8%, then if you tie up $30k in a new Prius V, say, you're missing out on $2400 a year you could be earning in returns from the stock market. Alternately, if you're financing that has its own interest rate. That significantly weighs the cost-of-ownership equation in favor of a cheaper ($2k-7k) car.

For insurance, likewise if you tied up that $30k in a new car, you've realistically got to insure that with collision insurance. That will cost you significantly more for insurance than for your Subaru which you probably just have liability on.

I'd say that if you can fit your stuff in a regular Prius, then for the number of miles you drive per year your most economical car will be a $4k-$7k 04-10 or so Prius. If that's not big enough for you, then maybe a Honda Fit or Toyota Matrix/Pontiac Vibe would be optimal. There are a few models that would be cheaper to run (Yaris, Echo, older civics and corollas) but I get the impression you'll need more space than they would give you. Although a 4-door Echo, while not a hatch, might surprise you.

mwcten,

I can't tell if you might be confusing the regular Prius, trim level V, with the Prius v, a larger Prius. I suggested the latter because it would have cargo volume closer to his Subaru. Though not necessarily a Prius v V (they started using Arabic numerals to avoid this confusion).

In thinking of the max budget of $30k, I was thinking of the new Prius V (the minivan-looking one) as the one you could get for $30k new, although I guess if you get a well speced out regular one (or if you're including taxes and fees) it hits that territory too. The Legacy wasn't that big of a car by todays standards; if I remember right it's smaller than the regular (non-C or V) Prius.