Well, you need to remember that the interest is calculated on the balance owed each month over the entire six year period. So it's more complicated than you've indicated here, and more expensive.
You need to get an amortization schedule from your credit union.
Or better yet, you might pick up an HP12C, which is an old financial calculator that I've been using to calculate the cost of loans for years.
If you want a quick and dirty shorthand, you gotta remember that the interest will accrue over 6 years, and your balance will decline over that same six year period. So you could do $750 x 6 = $4500, and then divide by two (because you'll be paying interest on a declining balance. So a quick and dirty estimate would be $2250 total payment on the credit union loan. A quick and dirty estimate on the Toyota loan would be $30,000 x 0.09, or $270, and take that x 6 = $1620 and then divide by two = $810. So you'll be paying about $1440 more in interest over the 6 years (quick and dirty) . . . I'd get the credit union loan and take the $2000. Just like MrsSope did with Toyota in December.
What car are you buying?