Refinance or hold?

I’m trying to wrap my head around the math regarding whether I should refinance my vehicle or not. My new goal is to pay off the car early. I haven’t had my credit pulled for rates yet but please let me know if it’s reasonable or not.

Details: Purchased Aug 2019 Excellent credit

Original loan: $42,000 Loan term: 60 mo Payments left: 34 Interest: 3.69% Monthly payment : $768 (min) Loan balance: $25,107 Car is now worth more than left on the loan, due to COVID.

Desired: New Loan term: 48 months

Potential Interest rate: 1.99% New Monthly payment: $545 Extra monthly principal payments: $223 ($768-$545)

1. Is it dumb or worth it to refinance for a lower rate?
2. Will I pay off the vehicle early by now applying the extra payments to principal?
3. Will I really save much?
4. Is going from 34 to 48 an okay thing?

Thank you.