First let me congratulate you for your plan, paying cash for your car.
Dave Ramsey would be proud of you.
I am assuming you will be contributing to the Car Savings Account periodically and have a 3 to 4 year time frame.
See if you can join a Credit Union.
Start saving by using a simple Share Savings account. Mine pays 1.51% APY.
Once you accumulate $1,000 buy a 6 month, 3.20% or a 12 month CD, 3.41%.
Continue until you have accumulated the amount you need to buy a nice gas guzzler.
Read “The Millionaire next door” and consider what the author says about cars.
There is a lot to be said for driving a junker.
Rossby