Is it a bad idea to roll an upsidedown carloan into your home refinance and pay it off?

Yes... it is,...
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Yes it is. You need to lower your debt, not increase it or move it around. With all of the financial messes that people have put themselves into. I am truly amazed at how little they've learned. They want to keep making the same mistakes.

Some simple guidelines:
1) Live within your means, spend less than you earn.
2) Do not take on any debt other than for your primary residence. Buy used cars until you save up enough to pay cash for new ones.
3) If you must finance a car, put at least 30% down and don't finance for more than 4 years. Otherwise you'll find yourself upside down like you now are.
4) Unless an emergency, never take equity out of your home. Your goal should always be to pay off the mortgage as soon as possible, not build on it.