Credit life insurance is purchased so that the balance of your car loan or credit line would be covered if you die before your debt is paid.
As with many of the policies in the Insurance You Can Do Without series, credit life insurance in too expensive compared to the premiums for term life insurance. With a set amount such as a car loan, this is made even worse since the amount insurance declines as you pay down the loan. The reason it declines with the amount owed is that this form of insurance only protects the bank that lent you the money. If you were to die, the pay out goes straight to the bank. With term life insurance, you set an amount to cover all your debts, plus an additional amount to cover your salary or maybe your children's education. If you're debt is reduced before you die, the insurance payout would still be at it's original amount, so your beneficiaries would receive a larger amount after the debts are paid.
If the cost of credit life insurance, compared to what you get for it, hasn't made you want to cancel and sign up for proper life insurance, then this might have you getting some life insurance quotes. If you've ever signed up for credit life insurance, did you notice how easy it is to get it? There are rather simple, vague health questions and no tests required. If you have a pre-existing condition, this might make you think that this type of insurance is easier to qualify for than term life insurance. The problem is that if you were to die and a claim is made, the insurance company would then begin their post-claim underwriting process. This means that the insurer will decide at that point if you actually qualify to receive a payout, even though you may have been paying premiums for years.
Instead of these loan-specific insurance policies, have a look at term life insurance. You can get an idea of the prices from different insurance companies at Kanetix.