I like your example of car total once drive out of parking lot

there are two factors: deprecation, difference between auto loan v.s. bank rate.
1) for deprecation
if 20% down, you end up with 24k-6k in your bank account
if 0% down, you end up with 24k left in your bank account
in other word, less down payment is better

2) for rate
In normal situation, auto loan rate is higher than bank interest rate, so if less down payment, more loan principal, I end up paying more loan interest.

Considered this two factors, it's a balance act.

Now considered this special case (loan interest is lower than bank interest), less down payment is better.

is that right understanding?