In a cosigned loan, both the signers are equally responsible for making the payments. Primary only means that person is the one expected to make normal payments.
If your friend isn't paying on time, the lender can certainly demand that you do so.
If it is a secured loan, they are entitled to demand that you sell the securing item to make those payments, or let them do so; that's what securing the loan with existing property means. This is essentially the same thing as repossession, though in that case the loan is secured by the item that was purchased.
However, they can't add collateral after the loan has been signed. So if they are threatening to take your car, either you agreed to that when you signed the loan, or they are suggesting that you could sell the car in order to make the payments but you can make them however you want, or they are lying to you in order to scare you into making payments more quickly.
Given the usurious interest rate (is this a credit card loan?), I would not be surprised by any of those three. This is not a loan your friend, or you, should have gone anywhere near.
You could try asking a lawyer to review the terms of the loan to make sure they aren't just lying. But as cosigners, you and your friend have to come up with the money somehow.
Given that high rate of interest again, one obvious suggestion is to refinance. That is, talk to banks about finding a loan with a more reasonable interest rate, and using that to pay off this one. If you can qualify for a more normal loan, the savings in interest could be HUGE. I have helped one relative, and one friend, arrange exactly this. In those cases, I was the one who took out the new loan, and I had my friend sending me checks to make the payments. If they had to skip a payment, I made it, and made a note that they owed me that payment plus interest. Less expensive, more straightforward, and realistically it's the same arrangement, and risks, as cosigning except that you, rather than the bank, have to keep track of what your friend still owes you.
Or, you could not bother taking out the loan, and just lend the friend your own money, assuming you have that much cash on hand. You would lose whatever interest you are gaining from whatever account that money is sitting in, but you wouldn't be paying interest. That may or may not be a better deal for you financially. Of course, you should still be charging your friend interest, to make up for the interest you are losing.
Those would be my recommendations now. You and your friend have the bad loan, with an awful interest rate. You and your friend have to pay it off. Taking a more reasonable loan, and paying it off in full now before it accrues more interest at that rate, is the best way out of this hole.
Next time, remember that if you are considering copaying, you are effectively taking out the loan on their behalf. If it isn't a reasonable loan, and if you wouldn't be willing to lend them your own money (since effectively that's what you're doing), don't do it. But for now, you're stuck, and may need to focus simply on limiting your losses until and unless your friend's finances improve.
And they owe you one hell of a favor.
