What DTI is acceptable for a car loan?

[fezwhy]

The refinance would be for a coworker. He has been making payments for a year. His score pulled at that time was around 540 on all 3 bureau's. He did get 2 credit cards shortly after to build credit. However he had his 2nd foreclosure about 2 years ago and missed student loan payments for a year. However the last missed payment was over 2 years ago.
Car value is 13.5k but he isn't sure how much is owed. I am guessing that with his payment at 381 a month he is underwater on the loan quite a bit.

[Remember0]

Well he really should find out his FICO and the principle balance remaining. It should be online for most lenders honestly or just call them? They have to tell you the baalnce remaining?

It's important because if he's upside down, he has to bring cash to the table to cover the gap between what's owed and NADA Retail typically. Also FICO is important so he knows which lenders to try first. Like if his EQ is below 620, I wouldn't recommend DCU. But if it's like closer to 650, DCU would be the first lender I tell him to try?

[fezwhy]

UPDATE:

My coworker was sent something for capitol one about refinancing his car loan.  They ran his credit and said he wouldn't be approved for the refinance. 

However they referred him to a credit union.  The credit union approved his refinance with a score of 620.  He went from a 15% to a 7% interest rate.

He gets 2k back and his loan payments are 50 bucks a month cheaper.  I told him to put that 2k down on his principle.  The catch is it puts him back to a 5 year loan again.  But he is happy with that.   I still can't believe he was approved considering has 2 foreclosures and a bankruptcy all within the last 10 years.  Not to mention all the lates on his student loan.  Let this be a lesson to anyone.  Don't think at least try before you say you won't be approved.