Why do I need to provide this?
Clark's Corvair now requires your CCV number on all credit card transactions.  This is to protect our customers from possible credit card fraud by 
providing an extra layer of security.  You can find your CCV number by looking at the examples below.
Visa Card
The CCV is a three-digit number on the back of your Visa card. The full credit card 
number is reprinted in the signature box and at the end of the number is the 
CCV.
Master Card

The CCV is a three-digit number on the back of your 
Master card. The full credit card number is reprinted in the signature box and 
at the end of the number is the CCV.
Discover Card

The CCV is a three-digit number on the back of your 
Discover card. The full credit card number is reprinted in the signature box and 
at the end of the number is the CCV. 
American Express Card

The CCV is a four-digit number on the front of the card above the credit card number on either the right or left side of your Amex card.