No, that's not necessary.
Well, you spelled the address wrong. The correct link is:
http://greenhybrid.com/compare/mileage/car/6933.html
Now go to User CP > Edit Signature and put this in the box:
HTML Code:
<a href="http://greenhybrid.com/compare/mileage/car/6933.html" style="border:0" title="Hybrid Cars Mileage"><img src="http://greenhybrid.com/compare/mileage/car/6933/signature.png" border=0 alt="Hybrid Cars Mileage"></a>