UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 1)

Quantum Fuel Systems Technologies Worldwide, Inc.

(Name of Issuer)

Common Stock, $0.02 par value

(Title of Class of Securities)

74765E109

(CUSIP Number)

Ryan J. York

Davis Wright Tremaine LLP

1201 Third Avenue, Suite 2200

Seattle, WA 98101

(206) 622-3150

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

January 18, 2014

(Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f), or 240.13d-1(g), check the following box.  ¨

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See § 240.13d-7 for other parties to whom copies are to be sent.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of Act but shall be subject to all other provisions of the Act (however, see the Notes).

Amendment No. 1 to Schedule 13D

Reference is hereby made to the statement on Schedule 13D filed with the SEC on September 27, 2013 (the “Original Schedule 13D” and, together with this Amendment No. 1, the “Schedule 13D”). Terms defined in the Schedule 13D are used herein as so defined.

The following items of the Schedule 13D are hereby amended as follows:

ITEM 4. PURPOSE OF TRANSACTION

The Filers hereby amend and restate this Item 4 as follows:

The Filers purchased the Convertible Notes and attached Warrants in a private placement transaction pursuant to a convertible note and warrant purchase agreement entered into by the Filers and the Issuer on September 15, 2013 (the “Purchase Agreement”), filed as Exhibit 7.2 to the Original Schedule 13D, that closed on September 18, 2013. The acquisition of the Convertible Notes, attached Warrants and Common Stock of the Issuer by the Filers was for investment purposes. In pursuing their investment purposes, the Filers may from time to time further purchase, hold, vote, trade, dispose of, engage in option, swap or other derivative securities transactions with respect to, or otherwise deal in the Common Stock at times, and in such manner, as they deem advisable to benefit from changes in the Common Stock’s market price, changes in the Issuer’s operations, business strategy or prospects, or from sale or merger of the Issuer. To evaluate such alternatives, the Filers routinely will monitor the Issuer’s operations, prospects, business development, management, competitive and strategic matters, capital structure and prevailing market conditions, as well as alternative investment opportunities, the Filers’ liquidity requirements and other investment considerations. Consistent with their investment research methods and evaluation criteria, the Filers may discuss such matters with the Issuer’s management, board of directors, other shareholders, industry analysts, existing or potential strategic partners or competitors, investment and financing professionals, sources of credit and other investors. Such factors and discussions may affect materially, and result in, the Filers’ modifying their ownership of the Common Stock. Other than the appointment of Tim McGaw on October 16, 2013 to serve on the Issuer’s Board of Directors as permitted under the Purchase Agreement, the Filers do not have any current intent to propose or take any of the actions described in paragraphs (a) through (j) of Item 4 of Schedule 13D, they may reconsider and change their plans or proposals relating to the Common Stock at any time.

ITEM 5. INTEREST IN SECURITIES OF THE ISSUER

The Filers update the disclosure in this Item 5 as follows:

The beneficial ownership of the Common Stock by each Filer at the date hereof is reflected on that Reporting Person’s cover page. This Amendment No. 1 reflects that the Warrants are exercisable within 60 days of the date hereof.

There were no transactions effected by the Filers in the Common Stock within the past sixty (60) days.

ITEM 6. CONTRACTS, AGREEMENTS, UNDERSTANDINGS OR RELATIONSHIPS WITH RESPECT TO SECURITIES OF THE ISSUER.

The Filers hereby add the following disclosure to this Item 6:

On October 16, 2013, the board of directors of the Issuer appointed Tim McGaw to serve on the Issuer’s board of directors, pursuant to the terms of the Purchase Agreement, Kevin Douglas, was given the right to appoint one member to the Issuer’s board of directors as long as his beneficial ownership is at least 5%. Tim McGaw will serve as a Class III director of the Issuer, which class will stand for re-election at the Issuer’s 2016 annual meeting of stockholders. In connection with the appointment of Tim McGaw to the Issuer’s board of directors, Tim McGaw entered into an Indemnification Agreement with the Issuer, the form of which has been filed as Exhibit 10.21 of the Issuer’s Registration Statement on Form S-1 (File No. 333-101668) filed with the SEC on December 5, 2002 and is incorporated herein by reference. In addition, on December 18, 2013, Tim McGaw was appointed to the Issuer’s Audit Committee.

ITEM 7. MATERIALS TO BE FILED AS EXHIBITS

The Filers hereby add the following disclosure to this Item 7:

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.