Definitely shop around, but sometimes the dealership does have an actual competitive offer. Especially if you threaten to use external financing (and have the pre approval in hand), they might knock down their interest rate to save the deal, as the loan is where the money actually is.
Nobody with financial sense is taking out a 16.9% loan on a car. 5% is pretty typical right now for people with a decent credit history.
Whether or not that’s reasonable, is certainly up for discussion.