Just got approved yesterday for my X100D with Alliant at 2.49%. That's their "special" rate for X100D....other models are different. All banks and CU's that I checked in my area are 4%+ for 100k+ at 72mo, so I think it's a good rate especially with prime rates increasing steadily. They also do tons of business with Tesla, so it was super simple, and my delivery specialist knew the Alliant guy and vice versa. 5-8 mins on the phone giving some details, approval email 5 minutes later. Boom. All info/funds transferred automatically down the road, no more work from me.
In the grand scheme of things, by all means shop for the best rate, but 0.1% or even 1% doesn't make that much of a difference. More importantly, you'll want to put as little down as possible with the low rates so you can use your cash for other investments that will make you money. (Assuming you can manage the higher monthly payment)