Originally Posted by eelhc

Not so...

Had he paid his dad the trade in value + taxes he would have had pay taxes on this total sum:

deal directly with Dad
assuming 8% sales tax
$13,901 (trade value or $14,200-$299) + his dad's tax savings ($1,112)
his total cost is $16,214 = 1.08 * ($13,901 + $1,112)

This way he pays taxes on:

deal through dealer
again assuming 8% sales
$14,200 = trade value + $299.
his total cost is $15,336 = 1.08 * $14,200

Pending the tax rate, he's

Given that all G35 drivers are good honest upstanding citizens who dutifully pay their correct and fair share of taxes he made out ahead

Congrats on your new car...