<PAGE>
 
                                                                   EXHIBIT 10.56

                                PROMISSORY NOTE


$15,000,000                                                   January 8, 1997
                                                              New York, New York

     FOR VALUE RECEIVED, Coinmach Laundry Corporation, a Delaware corporation
("Maker"), hereby unconditionally promises to pay to the order of Richard F.
Enthoven, as agent for and on behalf of each of the individuals listed on
                                                                         
Schedule A attached hereto ("Payee"), or to the Escrow Agent (as hereinafter
----------                                                                  
defined) as nominee for and on behalf of Payee, in each case subject to the
terms and conditions of this Promissory Note, in lawful money of the United
States of America and in immediately available funds, the principal sum of
Fifteen Million Dollars ($15,000,000) (the "Principal Amount"), in the amounts
and on the respective dates set forth on the amortization schedule attached
hereto, together with interest thereon at the rate of 9.875% per annum.
Interest shall accrue from the date hereof until this Promissory Note is paid in
full, shall be payable in arrears at the same time each installment of principal
is due and shall be computed based on a 360-day year in accordance with the
actual number of days elapsed.  In no event shall interest charged hereunder, in
whatever manner such rate of interest may be characterized or computed, exceed
the highest rate permissible under applicable law.

      All payments or prepayments of principal under this Promissory Note
(including any principal payments made as a result of the acceleration of any
payment obligations hereunder) shall be payable by Maker as follows:  (i) an
amount equal to seventy percent (70%) of each principal payment shall be paid to
Merrill Lynch Trust Co. (the "Escrow Agent"), to be held by the Escrow Agent
subject to the terms and conditions of that certain Escrow Agreement, dated as
of even date herewith by and among the Maker, Payee and the Escrow Agent (the
"Escrow Agreement"), and (ii) an amount equal to thirty percent (30%) of each
principal payment shall be paid to Payee.

     This Promissory Note is secured by a pledge of all of the capital stock of
Coinmach Corporation, a Delaware corporation and a wholly-owned subsidiary of
Maker, pursuant to that certain pledge agreement, dated as of even date
herewith, between the Maker and the Payee (the "Pledge Agreement"), the
provisions of which are incorporated herein by reference and form a part hereof.

     If (a) Maker fails to make any payment of principal or interest on this
Promissory Note when due, (b) a default in the payment of principal or interest
under the Credit Agreement (as defined in the Pledge Agreement) occurs and is
continuing, which default results in the acceleration of all of the indebtedness
thereunder prior to the express maturity thereof, or (c) a court of competent
jurisdiction enters a judgement, decree or order for relief in respect of the
Maker in an involuntary case or proceeding under any federal or state bankruptcy
law, which shall (i) approve as properly filed a petition seeking
reorganization,
<PAGE>
 
arrangement, adjustment or composition in respect of the Maker, (ii) appoint a
custodian, receiver, trustee, liquidator or similar official for the Maker or
for substantially all of its property or assets, or (iii) order the winding-up
or liquidation of its affairs, and such judgement, decree or order shall remain
unstayed and in effect for a period of sixty (60) consecutive days, then all
unpaid principal of and all accrued and unpaid interest on this Promissory Note
shall become and be immediately due and payable.

     Payment due under this Promissory Note may be offset by the Maker in the
event of any breach of or default under, or other claim by the Maker arising
under, that certain Stock Purchase Agreement, dated as of November 25, 1996, by
and among Maker, Payee and certain other parties thereto (the "Purchase
Agreement"), including, without limitation, any indemnity obligations arising
under Section 11.2(a) thereof, or any other agreement between the Maker and the
Payee executed in connection with the Purchase Agreement or contemplated
thereunder.  Any such offset (each, an "Offset") shall be treated as a
prepayment of principal due on this Promissory Note and applied against the next
succeeding payment or payments of principal due hereunder.  Any such Offset
hereunder shall be subject to the applicable provisions contained in the
Purchase Agreement and the Escrow Agreement.

     Any notice relating to this Promissory Note shall be in writing and shall
be deemed to be effective if given and received in the manner expressly provided
in the Purchase Agreement.

     This Promissory Note may be prepaid, in whole or in part, at any time
without penalty or premium, with interest to the date of such prepayment;
                                                                         
provided, however, that this Promissory Note shall be prepaid in part in a
--------  -------                                                         
principal amount of not less than $7,500,000 (net of any prepayments made
hereunder) on or prior to the date on which the Maker consummates the issuance
and sale, in an underwritten public offering, of shares of any class of Maker's
voting equity securities having an aggregate offering value of at least $50
million.  Any such prepayment (other than prepayments deemed to have been made
in connection with Offsets hereunder) shall be credited first against accrued
and unpaid interest and second against unpaid principal hereof.

     Maker hereby waives presentment for payment, demand, protest, notice of
protest and notice of dishonor or nonpayment of this Promissory Note.

     THIS PROMISSORY NOTE HAS BEEN DELIVERED AT AND SHALL BE DEEMED TO HAVE BEEN
MADE IN NEW YORK, NEW YORK AND SHALL BE INTERPRETED AND THE RIGHTS AND
LIABILITIES OF THE PARTIES HERETO SHALL BE DETERMINED IN ACCORDANCE WITH THE
INTERNAL LAWS AND DECISIONS OF THE STATE OF NEW YORK WITHOUT REGARD TO CONFLICTS
OF LAW PROVISIONS.

     EACH OF MAKER AND PAYEE IRREVOCABLY CONSENTS AND SUBMITS TO THE NON-
EXCLUSIVE JURISDICTION OF THE COURTS OF THE STATE OF NEW YORK AND THE UNITED
STATES DISTRICT COURT FOR THE SOUTHERN
<PAGE>
 
DISTRICT OF NEW YORK AND WAIVES ANY OBJECTION BASED ON VENUE OR FORUM NON
                                                                ----- ---
CONVENIENS WITH RESPECT TO ANY ACTION INSTITUTED THEREIN ARISING UNDER THIS
----------                                                                 
PROMISSORY NOTE OR IN ANY WAY CONNECTED WITH OR RELATED OR INCIDENTAL TO THE
DEALINGS OF MAKER AND PAYEE IN RESPECT OF THIS PROMISSORY NOTE OR THE
TRANSACTIONS RELATED HERETO, IN EACH CASE WHETHER NOW EXISTING OR HEREAFTER
ARISING, AND WHETHER IN CONTRACT, TORT, EQUITY OR OTHERWISE, AND AGREES THAT ANY
DISPUTE ARISING OUT OF THE RELATIONSHIP BETWEEN MAKER AND PAYEE OR THE CONDUCT
OF SUCH PERSONS IN CONNECTION WITH THIS PROMISSORY NOTE OR OTHERWISE SHALL BE
HEARD ONLY IN THE COURTS DESCRIBED ABOVE.  EACH OF MAKER AND PAYEE HEREBY WAIVES
PERSONAL SERVICE OF PROCESS AND AGREES THAT A SUMMONS AND COMPLAINT COMMENCING
AN ACTION OR PROCEEDING IN ANY SUCH COURT SHALL BE PROPERLY SERVED AND SHALL
CONFER PERSONAL JURISDICTION IF SERVED BY REGISTERED OR CERTIFIED MAIL TO SUCH
PARTY.  EACH OF MAKER AND PAYEE CONFIRMS THAT THE FOREGOING WAIVERS ARE INFORMED
AND FREELY MADE.

     Whenever possible each provision of this Promissory Note shall be
interpreted in such manner as to be effective and valid under applicable law,
but if any provision of this Promissory Note shall be prohibited by or invalid
under applicable law, such provision shall be ineffective only to the extent of
such prohibition or invalidity, without invalidating the remainder of such
provision or the remaining provisions of this Promissory Note.  All references
in this Promissory Note to Maker, Payee and Escrow Agent shall be deemed to
include, as applicable, a reference to their respective successors and assigns.
The provisions of this Promissory Note shall be binding upon and shall inure to
the benefit of the successors and assigns of Maker and the successors and
assigns of Payee.


     IN WITNESS WHEREOF, Maker has executed this Promissory Note as of the day
and year first written above.


                                    COINMACH LAUNDRY CORPORATION


                                        
                                    By: /s/ ROBERT M. DOYLE
                                        ----------------------------
                                        Name:  Robert M. Doyle
                                        Title: Senior Vice President
<PAGE>
 
                             AMORTIZATION SCHEDULE
<TABLE>
<CAPTION>
 
 
                    INSTALLMENTS    PORTION OF      PORTION OF
                    OF PRINCIPAL    PRINCIPAL       PRINCIPAL
                     TO BE PAID   INSTALLMENT TO  INSTALLMENT TO
                     ON PAYMENT     BE PAID TO      BE PAID TO
   PAYMENT DATE         DATE       ESCROW AGENT   SELLERS' AGENT
================================================================
<S>                 <C>           <C>             <C>
 
January 15, 1998      $1,000,000      $  700,000      $  300,000
 
January 15, 1999      $1,000,000      $  700,000      $  300,000
 
January 15, 2000      $2,000,000      $1,400,000      $  600,000
 
January 15, 2001      $2,000,000      $1,400,000      $  600,000
 
January 15, 2002      $2,000,000      $1,400,000      $  600,000
 
January 15, 2003      $3,000,000      $2,100,000      $  900,000
June 15, 2004         $4,000,000      $2,800,000      $1,200,000
================================================================
 
</TABLE>
<PAGE>
 
                         AMORTIZATION PAYMENT SCHEDULE
<TABLE>
<CAPTION>
 
 
                                            OFFSET OF
                PRINCIPAL  PRINCIPAL   PRINCIPAL PURSUANT
 PAYMENT DATE    PAYMENT   PREPAYMENT  TO ESCROW AGREEMENT
==========================================================
<S>             <C>        <C>         <C>
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
==========================================================
 
 
</TABLE>
<PAGE>
 
                                   SCHEDULE A
                                   ----------

                                LIST OF SELLERS



     Tamara Lynn Ford

     Robert Kyle Ford

     Traci Lea Ford

     Tucker F. Enthoven

     Richard F. Enthoven

     Richard Franklin Ford, Jr.,
     Trustee U/D/T February 4, 1994