LTV is the loan to value ratio, the value is dependant on the lender as some lender's use MSRP/NADA retail or NADA clean trade. For example if you were purchasing a truck from a dealer at $30,000 and the NADA clean trade value is $28,000 and you were financing say through Wells Fargo Dealer Services, you would have to finance only $22,400 to be at an LTV ratio of 80% which means you would need a down payment of $7,600.
Lender's like low LTV's because obviously it is a safer loan for them, if you were to default on the loan then the lender should be able to recoup any losses by selling the collateral at auction.
With sub-par credit, a higher down payment, lower LTV ratio, can often grant you an approval, sometimes with decent term's even.
In addition, in regard's to the previous comment, products that are purchased such as GAP, warranties, tire & wheel product's do not get considered in this LTV ratio as they are "back end products".
When a lender such as Wells Fargo, or Ally, etc approve a loan they give the dealer added room on the back-end for products. Let's say you finance a vehicle at 120% LTV on the "front end advance" these lender's may allow products to be added on the back end either specificed by a certain amount (say $4,000) or a "all in advance LTV" of 135-140%
