[al83s]

+1 on keeping the car.
I work at the car dealership and see people "downsize" all the time. They sell us their originally expensive cars that were half-way paid off and buy chevy aveos for similar money just to get the payment down. But guess what, now you have to pay this lower payments for another 4-6 years.
better option for them would be to just refinance their existing cars, raising their payment period back to 4 years granted you did not get a crap-load of student loans that have killed your credit.
That way - your payments are more affordable and if you have some left-over money - you can make an extra payment every now and then.
Yes, the parts for your boxster are more expensive than parts for a Yaris, but at least you have had your car for awhile and already know whats wrong/goes wrong where you can get a new car that will crap out on you too.
Also, it may seem wrong to install a set of Cheap tires, Autozone brake pads or have a tape covering the crack on the plastic window but those are the things you can live with untill your financial situation improves.

There is nothing wrong with having to stay at your moms till the rough patch is over. Times are tough and everybody has to deal with it one way or another.
Just my $.02