Question

In this sentence, are the quotation marks used correctly: When deciding on which automobile features to purchase, John said "yes" to the luxury package while Mary said "no".

Answer 1

To tell you the truth, you don't need the quotation marks, at all.
When deciding on which automobile features to purchase, John said yes to the luxury package, while Mary said no.

Or, you can do something like this:
"Yes!" said John, of the luxury package.
"No!" Marry countered.

Answer 2

You don't /need/ the quotes at all, actually :)

Answer 3

I guess that means the answer is NO.