<human>: In 2012, I desperately needed a car but I still had no credit so I went ahead and purchased a really cheap car that carried 18% interest. I am still paying for it now and still owe a little over $3000 on it. Couldn't refinance it because it is below refinancing minimum amount ($4K). Sell price according the KBB for it is estimated at $1500 - $2K, well below how much I still owe for it. 

A few days ago, wheel came loose while I was driving down the road. I had it repaired and it cost me $600 (it hasn't been a good week for me lately. Sigh.). I have a kid and I worry driving that car now with my kid in it. So I thought about just trading it in. 

Now, I have a good credit score (730 last I checked this month). If I trade it in, my understanding is I will be in an upside down. My thought is to have my balance carried over into the new loan and hopefully get a better interest rate. Can I do that? Would that be a good idea?

Can you give me a shortened version of the text?
<bot>: Trading in car I still owe money on, and will be in upside down, but I have better credit score now. Want to know if good idea.