Alliant offered it to me, but it was a little confused. I guess it depends on how much you finance for the loan and if you think there's a chance, should something happen that the value the insurance company gives you is less than the remaining amount of the loan.
For instance:
100k car, you fiancé 90k. If you have gap insurance and the car is totaled and insurance gives you $60k for the value of the car, gap insurance covers the difference from $60k to whatever is left on the loan.
If you finance less, say $50k. If you have gap insurance, and the car is totaled and insurance gives you 60k for the value of the car, gap insurance doesn't do anything for you as the insurance is enough to cover what's left on the loan.
Diminished value is something that's separate. What happens to the $30k-$40k from the $60k that insurance thinks the car is worth?