We traded in and have a new auto loan.  The paperwork that came with the loan stated ways to save money, and it gave an example of a loan with a principal amount similar to ours (let's say $25k) and an interest rate much higher than ours (5%) for 60 months (ours is 72).

It listed the amount saved over the life of the loan for paying $20 extra every month as $8xx
It listed the amount saved over the life of the loan for paying half payments every two weeks as $1,1xx

I'm planning it out to do both of those (half the minimum amount due +$10 every two weeks) and I'm not sure how to calculate how much I'm saving.

Our interest is 2.750000%, and the minimum due is $338.79 a month.    I'm paid the first payment as $360 since it's due soon, then I set it up to pay $180 every two weeks from here on out.

Now my math skills have deteriorated quite a bit since the last algebra class I took, so I'm in the dark trying to figure out how to add this up.   I'm pretty good with Excel but I'm not sure how to get it going.

I can't get Excel to match what is on my loan paperwork.  Maybe the compounding daily is what is different.