Depends on what you are sitting on for equity. I would ask at the bank what the rates will be for you first.
If you're under 80%, you can get a HELOC up to 80% and get some pretty good rates (make sure that you won't want another loan for awhile, because it will hurt your credit).
Otherwise it'll probably be cheaper for you to get a car loan.
(This is only speculation, ask your bank(s)).
Currently my HELOC rate would cost slightly less because the HELOCs are tax deductable (up to $100k) and offer more flexibility.
Don't forget that you can always pre-pay your loans. So what these people are saying about it costing you more is only relavant if you are not choosing to pay the same towards your HELOC that you'd be forced to pay on a car payment.
Also, all loans are "front-loaded" because you owe more when you start and you are making consistant payments (so more of it is interest when you start, and as you get it paid down, you owe less...so you pay interest on less).