As filed with the Securities and Exchange Commission on December 8, 2005

Registration No. 333-126944

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Amendment No. 5

to

Form S-1

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

DealerTrack Holdings, Inc.

(Exact name of registrant as specified in its charter)

1111 Marcus Avenue

Suite M04

Lake Success, New York 11042

(516) 734-3600

(Address, including zip code, and telephone number,

including area code, of the registrant’s principal executive offices)

Eric D. Jacobs, Esq.

Senior Vice President, General Counsel and Secretary

DealerTrack Holdings, Inc.

1111 Marcus Avenue

Suite M04

Lake Success, New York 11042

(516) 734-3600

(Name, address, including zip code, and telephone number,

including area code, of agent for service)

Copies to:

     Approximate date of commencement of proposed sale to the public: As soon as practicable after the effective date of this registration statement.

     If any of the securities being registered on this form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, check the following box.    o

     If this form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.    o

     If this form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.    o

     If this form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.    o

     If delivery of the prospectus is expected to be made pursuant to Rule 434, please check the following box.    o

CALCULATION OF REGISTRATION FEE

     The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until this Registration Statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

EXPLANATORY NOTE

      This Amendment No. 5 to the Registration Statement on Form S-1 of DealerTrack Holdings, Inc. is being filed for the purpose of filing a new Exhibit 1.1 hereto.

Part II

Information Not Required In Prospectus

      The actual and estimated expenses in connection with this offering, all of which will be borne by us, are as follows:

      We are incorporated under the laws of the State of Delaware. Section 145 of the Delaware General Corporation Law provides that a Delaware corporation may indemnify directors and officers as well as other employees and individuals against expenses (including attorneys’ fees), judgments, fines, and amounts paid in settlement in connection with specified actions, suits and proceedings, whether civil, criminal, administrative or investigative (other than action by or in the right of the corporation — a “derivative action”), if they acted in good faith and in a manner they reasonably believed to be in or not opposed to the best interests of the corporation and, with respect to any criminal action or proceeding, had no reasonable cause to believe their conduct was unlawful. A similar standard is applicable in the case of derivative actions, except that indemnification only extends to expenses (including attorneys’ fees) incurred in connection with the defense or settlement of such action, and the statute requires court approval before there can be any indemnification where the person seeking indemnification has been found liable to the corporation. The statute provides that it is not exclusive of other indemnification that may be granted by a corporation’s certificate of incorporation, by-laws, disinterested director vote, stockholder vote, agreement, or otherwise.

      The Delaware General Corporation Law further authorizes a Delaware corporation to purchase and maintain insurance on behalf of any person who is or was a director, officer, employee or agent of the corporation, or is or was serving at the request of the corporation as a director, officer, employee or agent of another corporation or enterprise, against any liability asserted against him and incurred by him in any such capacity, arising out of his status as such, whether or not the corporation would otherwise have the power to indemnify him under Section 145.

      Our fifth amended and restated certificate of incorporation that will be in effect upon completion of this offering limits the personal liability of directors for breach of fiduciary duty to the maximum extent permitted by the Delaware General Corporation Law. Except to the extent such exemption from liability is not permitted under the Delaware General Corporation Law, our fifth amended and restated certificate of incorporation provides that no director will have personal liability to us or to our stockholders for monetary damages for breach of fiduciary duty as a director. However, these provisions do not eliminate or limit the liability of any of our directors:

      Any amendment to or repeal of these provisions will not adversely affect any right or protection of our directors in respect of any act or failure to act occurring prior to any amendment or repeal or adoption of an inconsistent provision. If the Delaware General Corporation Law is amended to provide for further limitations on the personal liability of directors of corporations, then the personal liability of our directors will be further limited to the greatest extent permitted by the Delaware General Corporation Law.

      In addition, our by-laws provide that we must indemnify our directors and officers and we must advance expenses, including attorneys’ fees, to our directors and officers in connection with legal proceedings, subject to very limited exceptions. Acting pursuant to the foregoing, we have entered into agreements with each of our directors and officers to indemnify them to the fullest extent permitted by our restated certificate of incorporation, amended and restated by-laws and Delaware law.

      In addition, we have entered into indemnification agreements (the “Indemnification Agreements”) with some of our directors and officers. The Indemnification Agreements (i) confirm to officers and directors the indemnification provided to them in the amended and restated by-laws, (ii) provide officers and directors with procedural protections in the event that they are sued in their capacity as director or officer and (iii) provide additional indemnification rights.

      We have purchased insurance on behalf of our respective directors and officers against certain liabilities that may be asserted against, or incurred by, such persons in their capacities as our directors or officers, or that may arise out of their status as our directors or officers, including liabilities under the federal and state securities laws.

      In the preceding three years, the registrant has sold and issued the following securities that were not registered under the Securities Act:

      In addition, since January 1, 2002 we have granted 4,800,528 options to our directors, officers, employees, and an independent consultant. On various dates between January 1, 2002 and October 31, 2005, we sold 676,843 shares of our common stock to directors, officers and employees pursuant to the exercise of options granted under our 2001 Stock Option Plan. The exercise prices per share ranged from $2.80 to $8.00, for aggregate consideration of $1,650,873.

      The share numbers and prices above have been adjusted to reflect the 1-for-8 reverse stock split of the registrant’s common stock effected on March 19, 2003.

      The sales and issuances of securities in the transactions described in items 1, 2 and 3 above were determined to be exempt from registration under Section 4(2) of the Securities Act and Rule 506 of Regulation D thereunder as transactions by an issuer not involving a public offering. The sales and issuances of securities listed above in item 4 and the stock options granted since January 1, 2002 were deemed to be exempt from registration under the Securities Act in reliance on Rule 701 promulgated under Section 3(b) of the Securities Act as transactions pursuant to compensatory benefit plans and contracts relating to

compensation. The recipients of securities in each such transaction represented their intention to acquire the securities for investment only and not with a view to or for sale in connection with any distribution thereof and appropriate legends were affixed to the share certificates and other instruments issued in such transactions. All recipients either received adequate information about us or had access, through employment or other relationships, to such information. There were no underwriters employed in connection with any of the transactions set forth in this Item 15 other than Robertson Stephens, Inc. in connection with Item 1 above. All of the foregoing securities are deemed restricted securities for purposes of the Securities Act.

      (A) Exhibits. The following exhibits are included herein or incorporated herein by reference:

      (B) Financial Statement Schedules

      The undersigned registrant hereby undertakes:

Signatures

      Pursuant to the requirements of the Securities Act of 1933, DealerTrack Holdings, Inc. has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Lake Success, State of New York, on December 8, 2005.

      Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed by the following persons in the capacities and as of the dates indicated.

EXHIBIT INDEX