You can find out the most money they will loan you for a car loan when you approach your current bank/credit union. They should be willing to layout options based on your income, and credit history. You then have to decide if those terms work for you.
There are several dangers with getting loan estimates, they may be willing to lend you more than you can actually handle. They think you can afford it, but maybe you can't. They may also have a loan with a longer term, which does bring the monthly cost down, but exposes you to being upside down on the loan.
You then use this a a data point when looking at other lenders. The last place you look is the auto dealer. They will be trying to pressure you on both the loan and the price, that is not the time to do doing complex mental calculations.
The Suntrust web page was interesting, it included the quote:
The lowest rate in each range is for LightStream's unsecured auto loan
product and requires that you have an excellent credit profile.
It also induced the example the rate of 2.19% - 4.24% for a 24 to 36 month loan of $10,000 to $24,999 for a used car purchased from a dealer.
Also note that my local credit union has a new/used loan at 1.49%, but you have to be a member.
Sunstrust seems to be in the minority. In general a loan for X$ and y months will have a lower rate if it is secured with collateral. But Suntrust is offering unsecured loans (i.e. no collateral) at a low rate. The big benefit for their product is that you get the cash today. You can get the cash before you know what you want to buy. You get the cash before you have negotiated with the dealer. That makes that step easier.
Now will they in the near future ask for proof you bought a car with the money? no idea.
If you went to the same web page and wanted a debt consolidation loan the rate for the same $ range and the same months is: 5.49% - 11.24%
the quote now changes to:
The lowest rate in each range requires that you have an excellent
I have no idea what rate they will actually approve you for. It is possible that if you don't have excellent credit the rate rises quickly, but 4.24% for the worst auto loan is better than 5.49% for the best debt consolidation.
Given the unique nature of each individual’s credit situation,
LightStream believes there is no single definition for "excellent
credit". However, we find individuals with excellent credit usually
share the following characteristics:
- Five or more years of significant credit history.
- A credit history with a variety of account types such as major credit cards (for example, Visa, MasterCard, Amex), installment debt
(vehicle loans) and mortgage debt if applicable.
- An excellent payment history with no delinquencies or other problems repaying debt obligations.
- A proven ability to save evidenced by some or all of the following; liquid assets (stocks, bonds, bank deposits, etc.), cash
down payments on real estate, retirement savings, and little, if any,
revolving credit card debt.
- Stable and sufficient income and assets to easily repay current debt obligations and any new loan with LightStream.
Finally, it should be noted again that each individual situation is
different and that we make our credit judgment based on the specific
facts of that situation. Ultimately our determination of excellent
credit is based on whether we conclude that there is a very high
likelihood that our loan will be repaid in a full and timely manner.
All the rates mentioned in this answer are from 15 July 2017.