Taking out a HELOC for a car is absolutely the dumbest financial advice you can get. Not smart, ask Dave Ramsey.
Yes, we're huge Dave Ramsey fans.
In normal circumstances using a HELOC for a car purchase would not be smart. But times are different right now. If he has to finance its not the dumbest thing. Current used car rates are roughly 4+%, while HELOC rates are 3% (depending on your finances, equity etc). The mistake people would make is paying the minimum amount which would make it a 30yr loan. You just have to do the math and figure out how long you want to pay for it and make that your monthly payment.