If the car were appreciating in value (which it is not), then the $16,000 value after 8 years would be $16,000 ( 1 + 0.18)^8.
But the car is depreciating. Thus, the $16,000 value after 8 years would be
$16,000 ( 1 - 0.18)^8
or
$16,000 (0.82)^8 = $3,270.63
Great way to lose your money!