<PAGE>   1


                                                                    EXHIBIT 10.9


                                MCN ENERGY GROUP
                            SUPPLEMENTAL SAVINGS PLAN
                 (AS RESTATED EFFECTIVE AS OF DECEMBER 15, 1999)






<PAGE>   2




                                TABLE OF CONTENTS

<TABLE>
<CAPTION>

SECTION                                                                                                    PAGE
-------                                                                                                    ----
<S>                                                                                                        <C>
ARTICLE 1 - TITLE...........................................................................................1

ARTICLE 2 - DEFINITIONS.....................................................................................1

ARTICLE 3 - PURPOSE.........................................................................................1

ARTICLE 4 - EFFECTIVE DATE..................................................................................2

ARTICLE 5 - PARTICIPATION...................................................................................2

            Section 5.1 Eligibility to Participate..........................................................2
            Section 5.2 Election to Participate.............................................................2

ARTICLE 6 - PARTICIPANTS' ACCOUNTS..........................................................................3

            Section 6.1 Establishment of Accounts and Subordination of Executive's
                    Rights..................................................................................3
            Section 6.2 Credits and Debits to Participants' Accounts........................................3
            Section 6.3 Election of Accounts................................................................4
            Section 6.4 Change of Election for Accounts.....................................................5
            Section 6.5 Transfers Between Accounts..........................................................5

ARTICLE 7 - HARDSHIP WITHDRAWALS............................................................................5

ARTICLE 8 - VESTING AND PAYMENT OF BENEFITS.................................................................6

            Section 8.1 Form and Timing of Payments.........................................................6
            Section 8.2 Change in Payment Options...........................................................7
            Section 8.3 Payments Subject to Golden Parachute Provisions.....................................7
            Section 8.4 Vested Portion of Participants' Accounts............................................7
            Section 8.5 Recrediting of Forfeited Amounts....................................................7
            Section 8.6 Transfer to an Affiliated Company...................................................8

ARTICLE 9 - BENEFICIARY IN THE EVENT OF DEATH...............................................................8

ARTICLE 10 - ADMINISTRATION.................................................................................9

ARTICLE 11 - AMENDMENT AND TERMINATION......................................................................9
</TABLE>


                                       i
<PAGE>   3

<TABLE>
<S>                                                                                                       <C>
ARTICLE 12 - MISCELLANEOUS..................................................................................9

             Section 12.1 Non-Assignability.................................................................9
             Section 12.2 No Employment Rights.............................................................10
             Section 12.3 Law Applicable...................................................................10
             Section 12.4 Legal Fees and Expenses..........................................................10
             Section 12.5 Successors.......................................................................10

ARTICLE 13 - CHANGE IN CONTROL PROVISIONS..................................................................10

             Section 13.1 General..........................................................................10
             Section 13.2 Transfer to Rabbi Trust..........................................................10
             Section 13.3 Lump Sum Payments................................................................11
             Section 13.4 Joint and Several Liability......................................................11
             Section 13.5 Dispute Procedures...............................................................11
             Section 13.6 Definition of Change in Control..................................................11

Historical Background
</TABLE>


                                       ii
<PAGE>   4




                                MCN ENERGY GROUP
                            SUPPLEMENTAL SAVINGS PLAN
                 (AS RESTATED EFFECTIVE AS OF DECEMBER 15, 1999)



         WHEREAS, MCN Energy Group Inc. (the "Company") has previously adopted
the MichCon Supplemental Savings Plan and the Company desires to make certain
changes in the plan.

         NOW, THEREFORE, effective December 15, 1999, the MichCon Supplemental
Savings Plan is hereby amended and restated as follows:

                                    ARTICLE 1
                                      TITLE

         The title of this Plan shall be the "MCN Energy Group Supplemental
Savings Plan" and shall be referred to in this document as the "Plan".

                                    ARTICLE 2
                                   DEFINITIONS

         The words and phrases used in the Plan shall have the same meanings as
provided under Article 2 of the MCN Energy Group Savings and Stock Ownership
Plan (the "Qualified Plan"), as amended from time to time, unless otherwise
defined in the Plan or the context clearly requires otherwise.

                                    ARTICLE 3
                                     PURPOSE

         The principal purpose of the Plan is to provide deferred compensation
for a select group of management or highly compensated Employees of the Company
and any other Employer that has adopted the Plan with the consent of the Company
who has been specifically designated by the


<PAGE>   5


Committee to be eligible for Plan participation (an "Executive"). Such an
employee shall remain an Executive so long as this designation is not revoked by
the Committee.

It is intended that this Plan provide benefits for "a select group of management
or highly compensated employees" within the meaning of Section 201, 301 and 401
of ERISA and, therefore, to be exempt from the provisions of Parts 2, 3, and 4
of Title I of ERISA.

                                    ARTICLE 4
                                 EFFECTIVE DATE

         The original effective date of the Plan for the Company was May 31,
1988, and for any other Employer shall be the date established by such Employer
at the time of adoption of the Plan.

                                    ARTICLE 5
                                  PARTICIPATION

         Section 5.1 Eligibility to Participate. Only the following individuals
shall be eligible to participate in the Plan: (a) any Executive whose
contributions under the Qualified Plan are limited because of the limitation on
compensation under Section 401(a)(17) of the Code, the limitation on elective
deferrals under Section 402(g) of the Code, the limitation on benefits and
contributions under Section 415 of the Code, or any other provision of the Code
or other law that the Committee hereafter designates; and (b) such other
management or highly compensated Employees as shall be approved by the Chief
Executive Officer of an Employer that has adopted the Plan.

         Section 5.2 Election to Participate. An Executive who is eligible to
participate may become a participant in the Plan (a "Participant") by filing a
written election with the Committee on a form approved by the Committee. The
Executive's election shall authorize the Employer to defer the amount of such
Executive's Eligible Compensation pursuant to Section 6.2(a) and (c) hereof and
shall evidence the Executive's acceptance of and agreement to all the provisions
of the Plan.


<PAGE>   6

         The Executive's election must be made no later than December 31 of the
year that immediately precedes the year for which it applies. However, the first
election by any Executive to participate in this Plan shall be effective for
Eligible Compensation earned after the election is received by the Committee and
after contributions to the Qualified Plan are limited in accordance with Section
5.1(a) above. An election shall be irrevocable for the current calendar year. An
election shall be irrevocable for future calendar years unless a written
revocation is filed with the Committee prior to the first day of the calendar
year for which the revocation is desired.

                                    ARTICLE 6
                             PARTICIPANTS' ACCOUNTS

         Section 6.1 Establishment of Accounts. The Employer shall establish
accounts for each of its Executives who is a Participant in the Plan. Separate
accounts corresponding in name to the separate funds under the Qualified Plan
shall be maintained for each Participant. Credits under Sections 6.2(a) and (b)
shall also be maintained in separate accounts. The accounts shall be maintained
as unfunded bookkeeping accounts and all amounts represented by the accounts
shall remain a part of the general funds of the Employer of such Participant,
subject to the claims of its general creditors. Nothing in the Plan and no
action taken pursuant to the provisions of the Plan shall be deemed to create a
trust or fund of any kind or to create any fiduciary relationship. The
obligation to make payments under this Plan shall be and remain an unsecured,
unfunded general obligation of the Employer of the particular Participant. Each
Executive who is a Participant in the Plan shall be provided an annual statement
of the unfunded accounts maintained for the Participant.

         Section 6.2 Credits and Debits to Participants' Accounts. As of the end
of a pay period, total credits shall be made to the accounts maintained for a
Participant as set forth below:

         (a)       An amount equal to the difference between (1) and (2) below:

                        (1)  the amount that such Participant would have
                   contributed to the Qualified Plan for such pay period,
                   assuming (x) the Participant satisfied the eligibility
                   requirements set forth in Section 3.1 of the Qualified Plan
                   and (y) the allotments


                                       3
<PAGE>   7

                   of such Participant under the Qualified Plan were not limited
                   by the application of the any restriction set forth in
                   Section 5.1(a), or any provision of the Qualified Plan
                   relating to the limitations described in Section 5.1(a)
                   above;

                        (2)  the amount that such Participant actually
                   contributed to the Qualified Plan for such pay period.

         (b)       An amount equal to the difference between (1) and (2) below:

                        (1)  the amount that the Employer of such Participant
                   would have contributed to the Qualified Plan on behalf of
                   such Participant for such pay period if the Participant had
                   contributed the amount set forth in (a)(1) above to the
                   Qualified Plan during such pay period;

                        (2)  the amount that the Employer actually contributed
                   to the Qualified Plan on behalf of such Participant for such
                   pay period.

         The total credits under (a) and (b) of this Section shall be allocated
to the specific accounts elected by the Participant as provided under Section
6.3 hereof. Each account shall be credited with an amount representing earnings
or debited with an amount representing losses on a daily basis. Earnings or
losses for a pay period shall be calculated using the daily valuation
methodology employed by the recordkeeper for each corresponding fund under the
Qualified Plan.

         Section 6.3 Election of Accounts. Each Participant shall, by filing a
written election with the Committee, on a form approved by the Committee, elect
the accounts which are to be used for recording credits under Sections 6.2(a)
and (b) hereof.

         A Participant may direct that credits under Sections 6.2(a) and (b) may
be made to any account corresponding in name to the funds under the Qualified
Plan that are available to accept contributions or allotments. Notwithstanding
the foregoing, a Participant must at all times maintain an aggregate balance in
the MCN Stock fund in the Qualified Plan or the MCN Stock account in this Plan
or a combination of both such plans in an amount at least equal to the sum of
the Employer contributions made pursuant to Section 4.3(a) of the Qualified Plan
after April 1, 1989, plus seventy-five percent of


                                       4
<PAGE>   8

the credits recorded under Section 6.2(b) of this Plan (or the corresponding
Predecessor provision) after April 1, 1989. This balance may be maintained in
the Qualified Plan, this Plan, or a combination of both such plans, at the
discretion of the Participant.

         Section 6.4 Change of Election for Accounts. Any election of accounts
given by a Participant under the preceding Section shall be deemed to be a
continuing election until changed by the Participant. A Participant may change
any such election as of any normal business day of any month by giving prior
notice of such change to the Plan recordkeeper in the form prescribed by the
Committee.

         Section 6.5 Transfers Between Accounts. Transfers between accounts
shall be effected on any normal business day of any month upon directions to the
Plan recordkeeper in the form prescribed by the Committee.

         A Participant may not transfer any amount from the MCN Stock account if
the balance remaining in such account after the transfer would be less than the
amount required to be credited to such account under Section 6.3 hereof, plus
the earnings thereon.

                                    ARTICLE 7
                              HARDSHIP WITHDRAWALS

         A Participant may request, upon 20 days written notice to the
Committee, a withdrawal from his or her accounts if the withdrawal is on account
of financial hardship as defined under the Qualified Plan. A financial hardship
shall first be satisfied from the MCN Executive Deferred Compensation Plan to
the extent possible; then from the Plan; and finally from the Qualified Plan.
The amount of such withdrawal shall be limited to the amounts deferred under
Section 6.2(a) hereof, or the total value of the accounts maintained under
Section 6.2(a) hereof as of the end of the prior month, whichever is smaller.



                                       5

<PAGE>   9

         The determination of the existence of financial hardship and the amount
required to be distributed to meet the need created by the hardship shall be
made by the Committee. All determinations regarding financial hardship shall be
made in accordance with written procedures established by the Committee for
hardship withdrawals from the Qualified Plan and shall be applied in a uniform
and nondiscriminatory manner. Such written procedures shall specify the
requirements for requesting and receiving withdrawals on account of financial
hardship, including the forms that must be submitted, and to whom the forms are
to be submitted. No other withdrawals or loans are permitted under this Plan.

                                    ARTICLE 8
                         VESTING AND PAYMENT OF BENEFITS

         Section 8.1 Form and Timing of Payment. On the date that a Participant
becomes entitled, pursuant to either Section 9.1 or 9.2 of the Qualified Plan
(the "Retirement Date"), to a distribution of his or her account in the
Qualified Plan, such Participant shall be entitled to receive the vested portion
of the amount credited to his or her accounts in the Plan. All distributions
shall be paid out at the end of the quarter in which the Participant's
Retirement Date occurs. As of the end of the quarter in which his Retirement
Date occurs, the Participant's Account shall be valued on a cash basis with
interest credited annually at a rate equal to the average interest rate of
ten-year U.S. Treasury Notes for the November of the prior calendar year, or
such other rate as set by the Committee (the "Plan Interest Rate"). Payment of
the vested portion of a Participant's accounts shall be made in accordance with
the Participant's selection on his Benefit Agreement either in annual payments
over a period not less than one year and not more than 15 years, or in one lump
sum by the Employer maintaining the accounts. If no payment election has been
made, the vested portion of the Participant's account shall be paid in one lump
sum. The amount of the annual payments shall be calculated to pay out over the
specified period the entire balance in the Participant's Account as of his
Retirement Date with interest credited annually on the declining balance at the
Plan Interest Rate. The Participant's Account shall continue to be credited
annually with interest at the Plan Interest Rate and charged with the annual
payments to the Participant. The amount of the annual payments to the
Participant shall be adjusted at the end of the quarter in which the anniversary
of the Participant's retirement date




                                       6
<PAGE>   10

occurs to reflect changes in the Plan Interest Rate and other changes in the
Participant's Account balance.

         Section 8.2. Change in Payment Option. The payment option selected by
the Participant may be changed at any time by the Participant submitting a new
payment selection to the Committee, however, a change shall be effective only if
it is received by the Committee at least 12 months before payments under the
Plan commence.

         Section 8.3 Payments Subject to Golden Parachute Provisions.
Notwithstanding the above, if payment at the time specified in the first
sentence of this paragraph would subject the Participant to the excise tax under
Section 4999 of the Code, payment of the vested portion of a Participant's
accounts shall be deferred until the earlier of (a) the date that would have
been the Participant's Normal Retirement Date, Early Retirement Date or
Disability Retirement Date, (b) death of the Participant, or (c) total and
permanent disability or legally established mental incompetency of the
Participant.

         Section 8.4 Vested Portion of Participants' Accounts. The vested
portion of a Participant's account shall mean: (i) the total value of the
accounts of a Participant who is entitled to a distribution pursuant to Section
9.1 of the Qualified Plan; or (ii) with respect to a Participant who is entitled
to a distribution pursuant to Section 9.2 of the Qualified Plan, the total value
of the account maintained under Section 6.2(a) hereof. Notwithstanding the
foregoing, the total value of the accounts of a Participant shall become
nonforfeitable as of the date on which the Participant attains age 65.

         Section 8.5 Recrediting of Forfeited Amounts. If a Participant entitled
to a distribution pursuant to Section 9.2 of the Qualified Plan receives the
vested portion of the amount credited to his or her accounts in the Plan,
forfeits the remainder, and is thereafter reemployed prior to incurring five
consecutive Break in Service Years, then as of the end of the month coincident
with or next following the Participant's date of reemployment, the amount of the
Participant's accounts that was forfeited upon the earlier termination of
employment shall be credited to the Participant's accounts. Interest shall not
accrue on such amount between the time it was forfeited and the time at which it
was recredited.



                                       7
<PAGE>   11

         Section 8.6 Transfer to an Affiliated Company. Benefits for a
Participant who transfers employment from one Employer to an Affiliated Company
shall be subject to Section 3.8 of the Qualified Plan. Such a transfer of
employment shall cause a transfer of the accounts maintained by an Employer for
a Participant if the new Employer has adopted the Plan and the former Employer
transfers cash to the new Employer equal to the amount of the accounts
transferred. In all other events, a transfer of employment shall not cause a
transfer of the accounts maintained by an Employer for a Participant.

                                    ARTICLE 9
                        BENEFICIARY IN THE EVENT OF DEATH

         Each Participant shall have the right to designate a beneficiary or
beneficiaries to receive any distribution to be made under Article 8 upon the
death of such Participant, or, in the case of a Participant who dies subsequent
to termination of his or her employment but prior to the distribution of the
entire amount to which the Participant is entitled under the Plan, any
undistributed balance to which such Participant would have been entitled. Each
Participant shall also have the right to designate a contingent beneficiary in
the event any of the primary beneficiaries predecease the Participant or die
prior to complete disbursement of the Participant's account.

         If no beneficiary has been named by a Participant at the time of the
Participant's death, or if the beneficiary designated by the Participant has
predeceased the Participant or such designated beneficiary has died prior to
complete disbursement of the Participant's accounts and the Participant has
failed to name a contingent beneficiary, the value of the Participant's
accounts, or the undistributed portion thereof, shall be paid by the Employer to
the deceased employee's lawful successor(s) in interest in a lump sum as soon as
practicable, but in no event later than one year following the employee's death.


                                       8
<PAGE>   12
                                   ARTICLE 10
                                 ADMINISTRATION

         The Plan shall be administered by the Committee appointed pursuant to
the provisions of Section 10.1 of the Qualified Plan. The Committee shall have
the same powers and duties, and shall be subject to the same limitations, as are
described in the Qualified Plan. However, unlike the limitation on the
Committee's power to amend or modify the Qualified Plan under Section 11.1 of
the Qualified Plan, the Committee shall have full power to amend or modify the
Plan in all respects.

                                   ARTICLE 11
                            AMENDMENT AND TERMINATION

         The Company may amend or terminate the Plan at any time and for any
reason. The power to amend or modify the Plan shall rest solely with the
Committee. No such amendment or termination shall affect the rights of
Participants or beneficiaries to the vested portion of amounts credited to
Participants' accounts as of the date of such amendment or termination. In the
event of a termination of the Plan, all amounts credited to a Participant's
accounts shall be fully vested.


                                   ARTICLE 12
                                  MISCELLANEOUS

          12.1 Non-Assignability. This Plan shall be subject to the same terms
and conditions as specified in Section 15.4 of the Qualified Plan, and said
Section is hereby incorporated by reference.

         Section 12.2 No Employment Rights. Nothing contained in the Plan and no
action taken pursuant to the provisions of the Plan shall be construed as a
contract of employment between the Employer and an Employee, or as a right of
any Employee to be continued in the employment of the Employer, or as a
limitation of the right of the Employer to discharge any of its Employees at any
time, with or without cause, or as a limitation of the right of the Employee to
terminate employment at any time.



                                       9
<PAGE>   13

         Section 12.3 Law Applicable. This Plan and all actions hereunder shall
be governed by and construed according to the laws of the State of Michigan.

         Section 12.4 Legal Fees and Expenses. The Company shall pay all legal
fees and expenses which a Participant may incur as a result of the Company
contesting the validity, enforceability, or the Participant's interpretation of,
or determinations under this Plan other than the hardship withdrawal provisions
hereof.

         Section 12.5 Successors. In the event of any consolidation, merger,
acquisition or reorganization of the Company, the obligations of the Company
under this Plan shall continue and be binding upon the Company and its
successors.



                                   ARTICLE 13
                          CHANGE IN CONTROL PROVISIONS

         Section 13.1 General. In the event of a Change in Control, as defined
in Section 13.6, then, notwithstanding any other provision of the Plan, the
provisions of this Section 13 shall be applicable and shall supersede any
conflicting provisions of the Plan.

         Section 13.2 Transfer to Rabbi Trust. MCN Energy Group Inc. ("MCN") has
established a trust pursuant to a Trust Agreement dated January 3, 1991 (the
"Rabbi Trust"). The terms of the Rabbi Trust provide that, in the event of a
Change in Control and thereafter, assets are to be transferred to such trust to
provide benefits under the Plan. MCN shall make all transfers of funds required
by the Rabbi Trust in a timely manner and shall otherwise abide by the terms of
the Rabbi Trust.

         Section 13.3 Lump Sum Payments. In a Change in Control situation, the
Chairman of MCN shall have the absolute discretion to direct that a lump sum
payment be made to a Participant up to the total value of such Participant's
Account in the year of the Change in


                                       10
<PAGE>   14

Control if such payment will reduce the amount of any potential excise tax
imposed by Code Section 4999.

         Section 13.4 Joint and Several Liability. Upon and at all times after a
Change in Control, the liability under the Plan of MCN and each Affiliated
Employer that has adopted the Plan shall be joint and several so that MCN and
each such Affiliated Employer shall each be liable for all obligations under the
Plan to each employee covered by the Plan, regardless of the corporation by
which such employee is employed.

         Section 13.5 Dispute Procedures. In the event that, upon or at any time
subsequent to a Change in Control, a claim for benefits under the Plan of a
Participant or distributee who has exhausted the claims and appeals procedures
set forth in Section 10.6 of the Qualified Plan is denied in whole or in part,
the following additional procedures shall be applicable:

              (a)  Any amount that is not in dispute shall be paid to the
         Participant or distributee at the time or times provided herein.

              (b)  MCN shall advance to such claimant from time to time such
         amounts as shall be required to reimburse the claimant for reasonable
         legal fees, costs and expenses incurred by such claimant in seeking a
         judicial resolution of his or her claim, including reasonable fees,
         costs and expenses relating to appeals; provided, however, that MCN
         shall not be obligated to advance to the claimant any amounts under
         this Section 13.4(b) unless and until the claimant agrees in writing to
         repay to MCN, immediately upon the occurrence of a final judicial
         determination with respect to such dispute, any amount of such fees,
         costs and expenses that is not awarded to such claimant in a final
         order of a court of competent jurisdiction.

         Section 13.6   Definition of Change in Control.  A "Change of Control"
means:


                                       11
<PAGE>   15

              (a)  The acquisition by any individual, entity or group (within
         the meaning of Section 13(d)(3) or 14(d)(2) of the Securities Exchange
         Act of 1934, as amended (the "Exchange Act")) (a "Person") of
         beneficial ownership (within the meaning of Rule 13d-3 promulgated
         under the Exchange Act) of 20% or more of either (i) the then
         outstanding shares of common stock of MCN (the "Outstanding MCN Common
         Stock") or (ii) the combined voting power of the then outstanding
         voting securities of MCN entitled to vote generally in the election of
         directors (the "Outstanding MCN Voting Securities"); provided, however,
         that the following acquisitions shall not constitute a Change of
         Control: (A) any acquisition directly from MCN (excluding any
         acquisition by virtue of the exercise of a conversion privilege), (B)
         any acquisition by MCN, (C) any acquisition by any employee benefit
         plan (or related trust) sponsored or maintained by MCN or any
         corporation controlled by MCN or (D) any acquisition by any corporation
         pursuant to a reorganization, merger or consolidation, if, following
         such reorganization, merger or consolidation, the conditions described
         in clauses (i), (ii) and (iii) of subsection (c) of this Section 13.6
         are satisfied; or

              (b)  Individuals who, as of the date hereof, constitute the Board
         of Directors of MCN (the "Incumbent Board") cease for any reason to
         constitute at least a majority of the Board; provided, however, that
         any individual becoming a director subsequent to the date hereof whose
         election, or nomination for election by MCN's shareholders, was
         approved by a vote of at least a majority of the directors then
         comprising the Incumbent Board shall be considered as though such
         individual were a member of the Incumbent Board, but excluding, for
         this purpose, any such individual whose initial assumption of office
         occurs as a result of either an actual or threatened election contest
         (as such terms are used in Rule 14a-11 of Regulation 14A promulgated
         under the Exchange Act) or other actual or threatened solicitation of
         proxies or consents by or on behalf of a Person other than the Board;
         or

              (c)  Approval by the shareholders of MCN of a reorganization,
         merger or consolidation, in each case, unless, following such
         reorganization, merger or


                                       12
<PAGE>   16

         consolidation, (i) more than 60% of, respectively, the then outstanding
         shares of common stock of the corporation resulting from such
         reorganization, merger or consolidation and the combined voting power
         of the then outstanding voting securities of such corporation entitled
         to vote generally in the election of directors is then beneficially
         owned, directly or indirectly, by all or substantially all of the
         individuals and entities who were the beneficial owners, respectively,
         of the Outstanding MCN Common Stock and Outstanding MCN Voting
         Securities immediately prior to such reorganization, merger or
         consolidation in substantially the same proportions as their ownership,
         immediately prior to such reorganization, merger or consolidation, of
         the Outstanding MCN Common Stock and Outstanding MCN Voting Securities,
         as the case may be, (ii) no Person (excluding MCN, any employee benefit
         plan or related trust sponsored or maintained by MCN or any corporation
         controlled by MCN or such corporation resulting from such
         reorganization, merger or consolidation and any Person beneficially
         owning, immediately prior to such reorganization, merger or
         consolidation, directly or indirectly, 20% or more of the Outstanding
         MCN Common Stock or Outstanding MCN Voting Securities, as the case may
         be) beneficially owns, directly or indirectly, 20% or more of,
         respectively, the then outstanding shares of common stock of the
         corporation resulting from such reorganization, merger or consolidation
         or the combined voting power of the then outstanding voting securities
         of such corporation entitled to vote generally in the election of
         directors and (iii) at least a majority of the members of the board of
         directors of the corporation resulting from such reorganization, merger
         or consolidation were members of the Incumbent Board at the time of the
         execution of the initial agreement providing for such reorganization,
         merger or consolidation; or

              (d)  Approval by the shareholders of MCN of (i) a complete
         liquidation or dissolution of MCN or (ii) the sale or other disposition
         of all or substantially all of the assets of MCN, other than to a
         corporation, with respect to which following such sale or other
         disposition, (A) more than 60% of, respectively, the then outstanding
         shares of common stock of such corporation and the combined voting
         power of the then



                                       13
<PAGE>   17
         outstanding voting securities of such corporation entitled to vote
         generally in the election of directors is then beneficially owned,
         directly or indirectly, by all or substantially all of the individuals
         and entities who were the beneficial owners, respectively, of the
         Outstanding MCN Common Stock and Outstanding MCN Voting Securities
         immediately prior to such sale or other disposition in substantially
         the same proportion as their ownership, immediately prior to such sale
         or other disposition, of the Outstanding MCN Common Stock and
         Outstanding MCN Voting Securities, as the case may be, (B) no Person
         (excluding MCN Corporation, any employee benefit plan or related trust
         sponsored or maintained by MCN or any corporation controlled by MCN or
         such corporation resulting from such reorganization, merger or
         consolidation and any Person beneficially owning, immediately prior to
         such sale or other disposition, directly or indirectly, 20% or more of
         the Outstanding MCN Common Stock or Outstanding MCN Voting Securities,
         as the case may be) beneficially owns, directly or indirectly, 20% or
         more of, respectively, the then outstanding shares of common stock of
         such corporation and the combined voting power of the then outstanding
         voting securities of such corporation entitled to vote generally in the
         election of directors and (C) at least a majority of the members of the
         board of directors of such corporation were members of the Incumbent
         Board at the time of the execution of the initial agreement or action
         of the Board providing for such sale or other disposition of assets of
         MCN.


         IN WITNESS WHEREOF, the undersigned officer of the Company has executed
this Plan as of this 15th day of December, 1999.

                                  MCN ENERGY GROUP INC.


                                  By:
                                     -----------------------------------------
                                      Daniel L. Schiffer, Senior Vice President,
                                      General Counsel and Secretary



Restated: December 15, 1999




                                       14
<PAGE>   18



                              MCN ENERGY GROUP INC.
                            SUPPLEMENTAL SAVINGS PLAN

                              Historical Background

07/01/89          Plan amended and restated.

02/28/90          MCN Corporation Minutes of Regular Meeting of Board of
                  Directors - authorization for amendment regarding "Change in
                  Control" language (Section 13).

08/01/91          Plan amended and restated per MCN Corporation Minutes of
                  Regular Meeting of Board of Directors authorization for
                  amendment providing participants the option of receiving
                  essentially the same returns as available under the MichCon
                  Savings Plan, to require that participants maintain at least
                  75% of the employer matching portion in the Corporation's
                  common stock, and to conform the hardship withdrawal
                  provisions to new Treasury Regulations.

01/01/92          Amendment to Section 5.3, inserting at the end of Section 5.3
                  "and, when the Qualified Plan is amended to permit increased
                  Voluntary Deductions or Salary Reduction a change submitted
                  prior to the effective date of such amendments."

08/15/92          Plan restated.

01/01/97          Plan amended and restated per MCN Corporation Minutes of
                  Regular Meeting of Board of Directors as follows:

                  Article 1 is amended to reflect the change in the name of the
                  Plan to the "MCN Energy Group Inc. Supplemental Savings Plan".

                  Article 3 is amended to read as follows:

                        The principal purpose of the Plan is to provide deferred
                        compensation for a select group of management or highly
                        compensated Employees of the Company and any other
                        Employer that has adopted the Plan with the consent of
                        the Company who has been specifically designated by the
                        Committee to be eligible for Plan participation (an
                        "Executive"). Such an employee shall remain an Executive
                        so long as this designation is not revoked by the
                        Committee.

                        It is intended that this Plan provide benefits for "a
                        select group of management or highly compensated
                        employees" within the meaning of Section 201, 301 and
                        401 of ERISA and, therefore, to be exempt from the
                        provisions of Parts 2, 3, and 4 of Title I of ERISA.


                  Section 5.3 is amended to read as follows:

                        Section 5.3 Restriction on Change Deferrals Under the
                        Plan. The amount to be deferred by an Executive for a
                        Plan year shall be determined using the percentage of
                        his or her Compensation Rate in effect as of the
                        December 31 of the year which immediately precedes



<PAGE>   19

                        the year for which it applies. An Executive who elects
                        to participate in the Plan may not, after the effective
                        date of such election, change the percentage of his or
                        her Compensation Rate deferred under the Qualified Plan
                        to affect the amount to be deferred under the Plan
                        except for a change submitted prior to the first day of
                        the calendar year for which the change is desired, and,
                        when the Qualified Plan is amended to permit increased
                        Voluntary Reductions or Salary Reductions and such
                        change is submitted prior to the effective date of such
                        amendments. Any such other change in the percentage of
                        his or her Compensation Rate deferred under the
                        Qualified Plan shall be ignored for deferral purposes
                        under the Plan.

                  The heading of Section 6.1 is amended to read as follows:

                        Section 6.1  Establishment of Accounts and Subordination
                        of Executive's Rights.

                  Section 6.2 is amended to move the first paragraph to the end
                  of the section and to add a subparagraph (c) as follows:

                             (c) An amount of compensation equal to the
                             distribution of dividends on the MCN Stock held in
                             a Participant's Plan Account under the Qualified
                             Plan to the extent the Executive has not elected or
                             was ineligible to make Additional Allotments and
                             the Executive has elected to contribute such amount
                             to the Plan.

                             The total credits under (a) and (b) of this Section
                        shall be allocated to the specific accounts elected by
                        the Participant as provided under Section 6.3 hereof.
                        The credits under (c) of the Section shall be allocated
                        to the MCN Stock account in the Plan

                  Section 6.4 is amended as follows:

                        Any election of accounts given by a Participant under
                        the preceding Section shall be deemed to be a continuing
                        election until changed by the Participant. A Participant
                        may change any such election as of any normal business
                        day of any month by giving prior notice of such change
                        to the Plan recordkeeper in the form prescribed by the
                        Committee.


                  Article 7 is amended to add the following after the first
                  sentence in the article:

                        A financial hardship shall be satisfied from the MCN
                        Executive Deferred Compensation Plan to the extent
                        possible; then from the Plan; and finally from the
                        Qualified Plan.

                  Article 8 is amended to divide the information into sections
                  as follows:

<PAGE>   20

                             Section 8.1 Form and Timing of Payment. On the date
                        that a Participant becomes entitled, pursuant to either
                        Section 9.1 or 9.2 of the Qualified Plan (the
                        "Retirement Date"), to a distribution of his or her
                        account in the Qualified Plan, such Participant shall be
                        entitled to receive the vested portion of the amount
                        credited to his or her accounts in the Plan commencing
                        on the first of the month following the month in which
                        his Retirement Date occurs. As of the first of the month
                        following the month in which his Retirement Date occurs,
                        the Participant's Account shall be valued on a cash
                        basis with interest credited monthly at a rate equal to
                        the interest rate for the latest issue, as of the end of
                        the previous month, of ten-year U.S. Treasury Notes, or
                        such other rate as set by the Committee (the "Plan
                        Interest Rate"). Payment of the vested portion of a
                        Participant's accounts shall be made in accordance with
                        the Participant's selection on his Benefit Agreement
                        either in monthly payments in one-year increments, not
                        to exceed 15 years, or in one lump sum by the Employer
                        maintaining the accounts. The amount of the monthly
                        payments shall be calculated to pay out over the
                        specified period the entire balance in the Participant's
                        Account as of his Retirement Date with interest credited
                        monthly on the declining balance at the Plan Interest
                        Rate. The Participant's Account shall continue to be
                        credited monthly with interest at the Plan Interest Rate
                        and charged with the monthly payments to the
                        Participant. The amount of the monthly payments to the
                        Participant shall be adjusted on January 1 of each year
                        to reflect changes in the Plan Interest Rate and other
                        changes in the Participant's Account balance.

                             Section 8.2. Change in Payment Option. The payment
                        option selected by the Participant may be changed at any
                        time by the Participant submitting a new payment
                        selection to the Committee, by a change shall be
                        effective only if it is received by the Committee at
                        least 12 months before payments under the Plan commence.

                             Section 8.3 Payments Subject to Golden Parachute
                        Provisions. Notwithstanding the above, if payment at the
                        time specified in the first sentence of this paragraph
                        would subject the Participant to the excise tax under
                        Section 4999 of the Code, payment of the vested portion
                        of a Participant's accounts shall be deferred until the
                        earlier of (a) the date that would have been the
                        Participant's Normal Retirement Date, Early Retirement
                        Date or Disability Retirement Date, (b) death of the
                        Participant, or (c) total and permanent disability or
                        legally established mental incompetency of the
                        Participant.

                             Section 8.4 Vested Portion of Participants'
                        Accounts. The vested portion of a Participant's accounts
                        shall mean: (i) the total value of the accounts of a
                        Participant who is entitled to a distribution pursuant
                        to Section 9.1 of the Qualified Plan; or (ii) with
                        respect to a Participant who is entitled to a
                        distribution pursuant to Section 9.2 of the Qualified
                        Plan, the total value of the accounts maintained under
                        Sections 6.2(a) and (c) hereof. Notwithstanding the
                        foregoing, the total value of the accounts of a
                        Participant shall become nonforfeitable as of the date
                        on which the Participant attains age 65.



<PAGE>   21

                             Section 8.5 Recrediting of Forfeited Amounts. If a
                        Participant entitled to a distribution pursuant to
                        Section 9.2 of the Qualified Plan receives the vested
                        portion of the amount credited to his or her accounts in
                        the Plan, forfeits the remainder, and is thereafter
                        reemployed prior to incurring five consecutive Break in
                        Service Years, then as of the end of the month
                        coincident with or next following the Participant's date
                        of reemployment, the amount of the Participant's
                        accounts that was forfeited upon the earlier termination
                        of employment shall be credited to the Participant's
                        accounts. Interest shall not accrue on such amount
                        between the time it was forfeited and the time at which
                        it was recredited.

                             Section 8.6 Transfer to an Affiliated Company.
                        Benefits for a Participant who transfers employment from
                        one Employer to an Affiliated Company shall be subject
                        to Section 9.7(c) of the Qualified Plan. Such a transfer
                        of employment shall cause a transfer of the accounts
                        maintained by an Employer for a Participant if the new
                        Employer has adopted the Plan and the former Employer
                        transfers cash to the new Employer equal to the amount
                        of the accounts transferred. In all other events, a
                        transfer of employment shall not cause a transfer of the
                        accounts maintained by an Employer for a Participant.

                  Article 10 is amended as follows:

                        The Plan shall be administered by the Committee
                        appointed pursuant to the provisions of Section 10.1 of
                        the Qualified Plan. The Committee shall have the same
                        powers and duties, and shall be subject to the same
                        limitations, as are described in the Qualified Plan.
                        However, unlike the limitation on the Committee's power
                        to amend or modify the Qualified Plan under Section 11.1
                        of the Qualified Plan, the Committee shall have full
                        power to amend or modify the Plan in all respects.

                  Articles 12 and 13 are amended to update the references to the
                  sections in the Qualified Plan and to delete "Corporation"
                  after "MCN" in all cases after the term MCN has been defined.




11/29/99          Plan amended and restated as of 1/1/98 as follows:

                  Section 5.3 is deleted in its entirety. Prior to deletion,
                  previous Section 5.3 read as follows:

                             Section 5.3 Restriction on Change of Deferrals
                        Under the Plan. The amount to be deferred by an
                        Executive for a Plan year shall be determined using the
                        percentage of his or her Compensation Rate in effect as
                        of the December 31 of the year which immediately
                        precedes the year for which it applies. An Executive who
                        elects to participate in the Plan may not, after the
                        effective date of such election, change the percentage
                        of his or her Compensation Rate deferred under the


<PAGE>   22

                        Qualified Plan to affect the amount to be deferred under
                        the Plan, except for a change submitted prior to the
                        first day of the calendar year for which the change is
                        desired, and, when the Qualified Plan is amended to
                        permit increased Voluntary Reductions or Salary
                        Reductions and such change is submitted prior to the
                        effective date of such amendments. Any such other change
                        in the percentage of his or her Compensation Rate
                        deferred under the Qualified Plan shall be ignored for
                        deferral purposes under the Plan.

                  Section 6.2(a) is amended to delete reference to all of the
                  limitations listed in Section 5.1 and merely references
                  Section 5.1.

                  Section 6.2(c) is deleted in its entirety. Prior to deletion,
                  previous Section 6.2(c) read as follows:

                        An amount equal to the distribution of dividends on the
                        MCN Stock held in a Participant's Plan Account under the
                        Qualified Plan to the extent the Executive has not
                        elected or was ineligible to make Additional Allotments
                        and the Executive has elected to contribute such amount
                        to the Plan.

                  The last sentence of the first paragraph of the flush language
                  in Section 6.2 is deleted. Prior to deletion the sentence read
                  as follows:

                             The credits under (c) of this Section shall be
                        allocated to the MCN Stock account in this Plan.

                  The second to last sentence of the second paragraph of Article
                  7 is deleted. Prior to deletion, the sentence read as follows:

                             If a Participant receives a hardship withdrawal
                        from this Plan or from the Qualified Plan, no amounts
                        may be credited to the Participant's accounts under
                        Section 6.2(a) or (b) for a period of twelve months
                        after receipt of the hardship withdrawal.

                  Section 8.1 was amended to read as currently shown. Prior to
                  amendment, Section 8.1 read as follows:


                             Section 8.1 Form and Timing of Payment. On the date
                        that a Participant becomes entitled, pursuant to either
                        Section 9.1 or 9.2 of the Qualified Plan (the
                        "Retirement Date"), to a distribution of his or her
                        account in the Qualified Plan, such Participant shall be
                        entitled to receive the vested portion of the amount
                        credited to his or her accounts in the Plan commencing
                        on the first of the month following the month in which
                        his Retirement Date occurs. As of the first of the month
                        following the month in which his

<PAGE>   23


                        Retirement Date occurs, the Participant's Account shall
                        be valued on a cash basis with interest credited monthly
                        at a rate equal to the interest rate of ten-year U.S.
                        Treasury Notes, or such other rate as set by the
                        Committee (the "Plan Interest Rate"). Payment of the
                        vested portion of a Participant's accounts shall be made
                        in accordance with the Participant's selection on his
                        Benefit Agreement either in monthly payments in one-year
                        increments not to exceed 15 years, or in one lump sum by
                        the Employer maintaining the accounts. The amount of the
                        monthly payments shall be calculated to pay out over the
                        specified period the entire balance in the Participant's
                        Account as of his Retirement Date with interest credited
                        monthly on the declining balance at the Plan Interest
                        Rate. The Participant's Account shall continue to be
                        credited monthly with interest at the Plan Interest Rate
                        and charged with the monthly payments to the
                        Participant. The amount of the monthly payments to the
                        Participant shall be adjusted on January 1 of each year
                        to reflect changes in the Plan Interest Rate and other
                        changes in the Participant's Account balance.

                  Section 8.4 is amended to delete "and (c) hereof" at the end
                  of the first sentence.

                  The election and beneficiary designation forms are revised to
                  read as follows:



<PAGE>   24


                                MCN ENERGY GROUP
                            SUPPLEMENTAL SAVINGS PLAN

                             DEFERRAL ELECTION FORM

<TABLE>
<S><C>
================================================================================================================
Employee Name (Print)                          Social Security No.                          I. D. Number


----------------------------------------------------------------------------------------------------------------
Address (Number/Street)                        City                           State         Zip Code


================================================================================================================

Deferral Election

[ ]      In accordance with the terms of the MCN Energy Group Supplemental
         Savings Plan ("Plan") which is hereby incorporated by reference, I
         hereby accept and agree to all the provisions of the Plan and
         irrevocably elect pursuant to Section 5.2 of the Plan to defer a
         portion of my compensation pursuant to Section 6.2 of the Plan.

[ ]      I elect NOT to participate in the MCN Energy Group Supplemental Savings
         Plan.

Payment Election

I elect to have the amount I have deferred paid to me after termination of my
employment with the Company and its subsidiaries by reason of retirement,
disability, or death, in the manner specified below:

[ ]      Lump-sum payment.

[ ]      Payment in annual installments over       years (in one year
         increments, not to exceed 15 years).

I understand that if I fail to make a payment election, my MCN Energy Group
Supplemental Savings Plan account balance will be paid in a lump sum at the end
of the quarter in which my Retirement Date (as defined in Section 8.1) occurs.

I understand that, in addition to the above payment, I may be eligible for a
hardship withdrawal pursuant to Article 7 of the Plan.

================================================================================================================
Employee Signature                                                                     Date


----------------------------------------------------------------------------------------------------------------
Receipt Acknowledged By                           Title                                Date


================================================================================================================
</TABLE>

Revised March 18, 2000

<PAGE>   25



                                MCN ENERGY GROUP
                            SUPPLEMENTAL SAVINGS PLAN

                          BENEFICIARY DESIGNATION FORM
<TABLE>
<S><C>
============================================================================================================================
Employee Name (Print)                                    Social Security No.                            I. D. Number


============================================================================================================================
Address (Number/Street)                                  City                            State          Zip Code


============================================================================================================================

I hereby designate, pursuant to Article 9 of the above-referenced plan, the
below-designated person(s) as my beneficiary in the event of my death:

===========================================================================================================================
Beneficiary's Name                                             Address

---------------------------------------------------------------------------------------------------------------------------


---------------------------------------------------------------------------------------------------------------------------


---------------------------------------------------------------------------------------------------------------------------

I UNDERSTAND THAT THE DESIGNATION OF A BENEFICIARY OTHER THAN MY SPOUSE MUST BE
CONSENTED TO IN WRITING BY MY spouse.

In the event any of the above-named beneficiaries should predecease me, or shall
survive me but die before receiving all amounts to be paid, I hereby name the
following as a contingent beneficiary to receive any such unpaid amounts:

===========================================================================================================================
Beneficiary's Name                                             Address

---------------------------------------------------------------------------------------------------------------------------


---------------------------------------------------------------------------------------------------------------------------


---------------------------------------------------------------------------------------------------------------------------

In the event none of the above-named beneficiaries survive me, any unpaid
amounts shall be paid to my lawful successor in interest. I reserve the right to
change this beneficiary designation at any time by filing with the Committee or
its Designee a new beneficiary designation form.

I UNDERSTAND THAT MY MOST RECENT ELECTION AS TO THE BENEFICIARY DESIGNATION WILL
APPLY TO ALL DEFERRALS BY ME UNDER THE PLAN.

=========================================================================================================================
Employee Signature                                                                     Date


-------------------------------------------------------------------------------------------------------------------------
Receipt Acknowledged By                           Title                                Date


=========================================================================================================================

SPOUSAL CONSENT:  I HEREBY CONSENT TO THE DESIGNATION OF BENEFICIARY SET FORTH
HEREIN.

=========================================================================================================================
Spouse's Signature                                                    Date


-------------------------------------------------------------------------------------------------------------------------
Witness                                                               Date


=========================================================================================================================
</TABLE>


<PAGE>   26


12/15/99          The Plan was amended and restated as of December 15, 1999 to
                  reflect the following changes:

                  New Section 12.5 was added to read as shown.

                  Sections 13.3, 13.4 and 13.5 were redesignated as Sections
                  13.4, 13.5 and 13.6, respectively. A new Section 13.3, Lump
                  Sum Payments, was added to read as shown.