REVOLVING CREDIT NOTE

Exhibit 10.5

REVOLVING CREDIT NOTE

On or before the Maturity Date, FOR VALUE RECEIVED, Quantum Fuel Systems Technologies Worldwide, Inc., a Delaware corporation (the " Company "), promises to pay to the order of WB QT, LLC, a Delaware limited liability company (" Lender ") at Minneapolis, Minnesota, care of the Agent in lawful money of the United States of America so much of the sum of Twenty Million Six Hundred Thirty-Seven Thousand Five Hundred Dollars ($20,637,500), as may from time to time have been advanced by Lender to the Company and then be outstanding hereunder pursuant to the Credit Agreement dated as of January 31, 2007 made by and among the Company and certain lenders signatory thereto, including the Lender, and WB QT, LLC as Agent for such lenders, as the same may be amended or otherwise modified from time to time (" Credit Agreement "), together with interest thereon as hereinafter set forth.

Each of the Revolving Credit Advances made hereunder shall bear interest at the interest rate from time to time app