I've always gone through lightstream, outside of special dealer/manufacturer financing , rates are roughly the same everywhere. Upside of lightsream is they are an unsecured loan (doesn't hold title/lein. Just ACHs you the money within 1-2 days ) They will also beat any other rate you are approved for by .1%
Yes, but always come into the dealership with a strong pre-approved rate from a bank or usually better, a credit union even if you already have a strong credit score. Dealers make some profit off of selling a rate higher than what they can offer at times, so it’s good to have something for them to beat in your back pocket to introduce if their offer doesn’t significantly beat your pre-approved rate.
That said, on new cars what you can negotiate up front on selling price and trade can leave small margins for the dealer already that they are expecting to make up in finance and selling you products (like extended warranties) in finance so if you have already grinded them hard negotiating selling price and trade in price and you give a damn about local businesses, maybe let up a bit when you’re in front of the finance person.