<PAGE>   1
 
================================================================================
 
                                 UNITED STATES
 
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
 
                                   FORM 10-K
 
(MARK ONE)
[X]   ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE
                SECURITIES EXCHANGE ACT OF 1934 [FEE REQUIRED]
 
                  FOR THE FISCAL YEAR ENDED DECEMBER 31, 1997
 
                                       OR
 
[  ]   TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE
                 SECURITIES EXCHANGE ACT OF 1934 [NO FEE REQUIRED]
 
        FOR THE TRANSITION PERIOD FROM ______________ TO ______________
 
                          COMMISSION FILE NO. 2-80930
 
                        DEL TACO RESTAURANT PROPERTIES I
                       (A CALIFORNIA LIMITED PARTNERSHIP)
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
 
                                   CALIFORNIA
                        (STATE OR OTHER JURISDICTION OF
                         INCORPORATION OR ORGANIZATION)
 
                          23041 AVENIDA DE LA CARLOTA
                            LAGUNA HILLS, CALIFORNIA
                    (ADDRESS OF PRINCIPAL EXECUTIVE OFFICES)
 
                                   95-3852699
                                (I.R.S. EMPLOYER
                             IDENTIFICATION NUMBER)
 
                                     92653
                                   (ZIP CODE)
 
       REGISTRANT'S TELEPHONE NUMBER, INCLUDING AREA CODE: (714) 462-9300
 
        SECURITIES REGISTERED PURSUANT TO SECTION 12(B) OF THE ACT: NONE
 
        SECURITIES REGISTERED PURSUANT TO SECTION 12(G) OF THE ACT: NONE
 
     Indicate by check mark whether the registrant (1) has filed all reports
required to be filed by Section 13 or 15(d) of the Securities Exchange Act of
1934 during the preceding 12 months (or for such shorter period that the
registrant was required to file such reports), and (2) has been subject to such
filing requirements for the past 90 days.     Yes  X      No ___
 
                      DOCUMENTS INCORPORATED BY REFERENCE
 
     Portions of the registrant's Form S-11 Registration Statement filed
December 17, 1982 are incorporated by reference into Part IV of this report.
 
================================================================================
<PAGE>   2
                                     PART I

ITEM 1. BUSINESS

The Registrant is a publicly-held Limited Partnership organized under the
California Uniform Limited Partnership Act. In accordance with the Partnership
Agreement, the Registrant's General Partner is Del Taco, Inc., a California
corporation ("General Partner"). The Registrant sold 8,751 Units aggregating
$4,375,500 through an offering of Limited Partnership Units from March 21, 1983
through March 20, 1984.

The Registrant has engaged in the business of acquiring sites in California for
the construction of six Mexican-American restaurants for long-term lease to Del
Taco, Inc. for operation under the Del Taco trade name. Each Property is leased
for 35 years on a triple-net basis for a rent equal to twelve percent of gross
sales of the restaurant constructed thereon. The activities of the Registrant
relating to acquisition and development of the Properties is presented under
Item 2 below. The term of the Partnership Agreement is until April 30, 2022,
unless terminated earlier by means provided therein.

Because the six Properties owned by the Registrant constitute virtually all of
the Registrant's income producing assets, the business of the Registrant is
almost entirely dependent on the success of the Del Taco trade name restaurants
which lease those Properties. In turn, the success of those restaurants, which
are not operated by the Registrant, is dependent on a large variety of factors,
including, but not limited to, consumer demand and preference for fast food, in
general, and for Mexican-American food in particular.

The Registrant has no full time employees. The General Partner is vested with
full authority as to the general management and supervision of the business and
affairs of the Registrant, and has a one percent interest in the profits and
distributions of the Registrant. Limited Partners have no right to participate
in the management or conduct of such business and affairs.


                                       2
<PAGE>   3
ITEM 2. PROPERTIES

The Registrant has acquired six Properties with proceeds obtained from the sale
of Limited Partnership Units:

<TABLE>
<CAPTION>
                                                                                      Date of 
                                            Date of            Restaurant             Commencement
Address              City, State            Acquisition        Constructed            of Operation(1)
-------              -----------            -----------        -----------            ----------------
<S>                  <C>                    <C>                <C>                    <C>    

Riverside Avenue     Rialto, CA             September 28,      60 seat with drive     February 12, 1985
                                            1984               through service
                                                               window
Elden                Moreno Valley, CA      March 8, 1985      60 seat with drive     June 30,
Avenue                                                         through service        1985
                                                               window
Foothill Boulevard   La Verne, CA           April 16, 1985     60 seat with drive     November 6,
                                                               through service        1985
                                                               window
Baseline &           Rancho Cucamonga, CA   July 10, 1985      60 seat with drive     November 26, 1985
Archibald                                                      through service
                                                               window
Elkhorn Boulevard    Sacramento, CA         August 22, 1985    60 seat with drive     January 15,
                                                               through service        1986
                                                               window
Haven                Rancho Cucamonga, CA   September 20,      60 seat with drive     February 14, 1986
Avenue                                      1985               through service
                                                               window
</TABLE>

(1)   Commencement of operation is the first date Del Taco, Inc., as lessee,
      operated the facility on the site as a Del Taco restaurant.


                                       3
<PAGE>   4
                                     PART II


ITEM 3. LEGAL PROCEEDINGS

The Registrant is not a party to any material pending legal proceedings.

ITEM 4. SUBMISSIONS OF MATTERS TO A VOTE OF SECURITY HOLDERS

None.

ITEM 5. MARKET FOR THE REGISTRANT'S COMMON EQUITY AND RELATED SECURITY HOLDER
        MATTERS

The Registrant, a publicly-held Limited Partnership, sold 8,751 ($4,375,500)
Limited Partnership Units during the offering period ended March 20, 1984 and
currently has 992 Limited Partners of record. There is no public market for the
trading of the Units. Distributions made by the Registrant to the Limited
Partners during the past three fiscal years are described in Note 7 to the Notes
to the Financial Statements contained under Item 8.


                                       4
<PAGE>   5
ITEM 6. SELECTED FINANCIAL DATA


<TABLE>
<CAPTION>
                                                    For the Year Ended December 31, 
                               1997             1996             1995             1994             1993
                            ----------       ----------       ----------       ----------       ----------
<S>                         <C>              <C>              <C>              <C>              <C>       

Rental Revenue              $  487,280       $  452,203       $  436,262       $  420,245       $  421,178

Interest and                     5,109            2,902            2,729            2,729            3,281
 other income

Net income                     403,356          365,387          275,020          222,295          233,111

Net income
 per limited
 Partnership
 Unit(1)                         45.63            41.34            31.11            25.15            26.37

Cash Distributions
 per Limited
 Partnership
 Unit(2)(3)(4)(5)(6)             49.28            44.82            45.70            58.70            18.49

Total Assets                 2,515,808        2,543,173        2,569,140        2,700,433        2,993,046

Long-term
 Obligations                      None             None             None             None             None
</TABLE>

(1)   The net income per Limited Partnership Unit was calculated based upon
      8,751 weighted average Units outstanding for all years presented.

(2)   Two quarterly distributions were disbursed during the year ended December
      31, 1993. Cash distributions for the quarters ended September 30, 1993 and
      December 31, 1993 amounted to $24.95 and were paid January 31, 1994 and
      February 2, 1994, respectively.

(3)   Cash distributions for the quarter ended December 31, 1994 amounted to
      $11.70 per Limited Partnership Unit and were paid January 17, 1995. Five
      distributions were disbursed during the year ended December 31, 1994.


                                       5
<PAGE>   6
ITEM 6. SELECTED FINANCIAL DATA - CONTINUED

(4)   Cash distributions for the quarter ended December 31, 1995 amounted to
      $11.46 per Limited Partnership Unit and were paid January 15, 1996. Four
      distributions were disbursed during the year ended December 31, 1995.

(5)   Cash distributions for the quarter ended December 31, 1996 amounted to
      $12.63 per Limited Partnership Unit and were paid January 31, 1997. Four
      distributions were disbursed during the year ended December 31, 1996.

(6)   Cash distributions for the quarter ended December 31, 1997 amounted to
      $11.59 per Limited Partnership Unit and were paid January 31, 1998. Four
      distributions were disbursed during the year ended December 31, 1997.

ITEM 7. MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS
        OF OPERATIONS

Liquidity and Capital Resources

The Registrant commenced offering of Limited Partnership Units on March 21,
1983. By March 20, 1984, the sale of such Units provided a total capitalization
for the Registrant of $4,375,500. Fifteen percent of the cash received from the
sale of Limited Partnership Units was used to pay commissions to brokers and to
reimburse the General Partner for offering costs incurred. The remaining funds
were expended for the acquisition of sites and construction of six restaurants.
In 1985, the first four restaurants opened for business and two additional
restaurants were opened in 1986. Approximately $4,002,000 was expended for such
purposes.

Since the six restaurants owned by the Registrant opened, cash flow from lease
payments received from Del Taco, the Registrant's General Partner, which leases
all six restaurants, two of which have been subleased to Del Taco franchisees
(one of which is affiliated with Del Taco, Inc.) has provided adequate liquidity
for operation of the Registrant. However, the Registrant's overwhelmingly
predominant source of income to meet its expenses and fund distributions to its
Limited Partners is payments from Del Taco (and, as to one of the Properties,
Del Taco's sub-lessee) under the Leases, comprising primarily rent calculated on
the basis of the gross sales of the restaurants operated on the Properties, as
to which there are no contractually specified minimum or guaranteed amounts.
Thus, the adequacy of the Registrant's liquidity and capital resources in the
future will depend primarily upon the gross revenues of such restaurants as well
as upon Del Taco's financial condition and results of operations generally.


                                       6
<PAGE>   7
ITEM 7. MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS
        OF OPERATIONS - CONTINUED

Results of Operations

The Registrant owns six Properties that are under long-term lease to Del Taco
for restaurant operations (Del Taco, in turn, has subleased two of the
restaurants to Del Taco franchisees, one of which is affiliated with Del Taco).
The Registrant receives rental revenues equal to 12 percent of restaurant sales.
The Registrant had rental revenues of $487,280 for the year ended December 31,
1997, representing an increase from the rental revenues of $452,203 in 1996.
Such increase is directly attributable to increased sales at the restaurants.

The following table sets forth rental revenue earned by restaurant for the year:


<TABLE>
<CAPTION>
                                                                 YEAR ENDED
                                                                DECEMBER 31,
                                                     1997           1996           1995
                                                 ------------   ------------   ------------
<S>                                              <C>            <C>            <C>         

Riverside Avenue, Rialto, CA                     $     80,255   $     67,599   $     59,914

Elden Avenue, Moreno Valley, CA                        73,557         72,988         79,859

Foothill Boulevard, La Verne, CA                      105,677        100,030         90,283

Baseline & Archibald, Rancho Cucamonga, CA             73,553         64,636         61,958

Elkhorn Boulevard, Sacramento, CA                      49,752         45,528         46,339

Haven Avenue, Rancho Cucamonga, CA                    104,486        101,422         97,909
                                                 ------------   ------------   ------------
           Total                                 $    487,280   $    452,203   $    436,262
                                                 ============   ============   ============
</TABLE>

The following table sets forth, for the periods indicated, the percentage
relationship to total general and administrative expenses, of items included in
the Registrant's Statements of Income:

                  PERCENTAGE OF TOTAL GENERAL & ADMIN. EXPENSE

<TABLE>
<CAPTION>
                                 Year Ended December 31,
                             1997          1996          1995
                            -----         -----         ----- 
<S>                         <C>           <C>           <C>   

Accounting fees             32.70%        36.02%        35.17%
Distribution of
 information to
 Limited Partners           65.53         61.43         62.35
Legal fees                     --            --         -0.76
Other                        1.77          2.55          3.24
                           ------        ------        ------ 
                           100.00%       100.00%       100.00%
                           ======        ======        ====== 
</TABLE>


                                       7
<PAGE>   8
ITEM 7. MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS
        OF OPERATIONS - CONTINUED

Operating expenses include general and administrative expenses which consist
primarily of accounting fees and costs of distribution of information to the
Limited Partners. For the year ended December 31, general and administrative
expenses decreased from $45,943 in 1996 to $45,261 in 1997 reflecting lower
costs for accounting and distribution of information to the limited Partners.

The Registrant incurred depreciation expense in the amount of $43,772 for the
year ended December 31, 1997, $43,775 for the year ended December 31, 1996 and
$121,530 for the year ended December 31, 1995. Depreciation expense decreased
because signs and equipment became fully depreciated during 1996.

For the reasons stated under "Liquidity and Capital Resources" above, the
Registrant's results of operations in the future will depend primarily upon the
gross revenues of the restaurants located on the Properties leased to Del Taco
as well as upon Del Taco's financial condition and results of operations
generally.

Management does not believe the operations of the Company will be significantly
impacted by the year 2000 software issue and does not believe the year 2000
software issue will materially effect the Company's operations, financial
position or cash flows.


                                       8
<PAGE>   9
ITEM 8. FINANCIAL STATEMENTS

PART I. INFORMATION


<TABLE>
<CAPTION>
                                   INDEX                   PAGE NUMBER
                                   -----                   -----------
<S>                                                        <C>

Report of Independent Public Accountants                       10

Balance Sheets at December 31, 1997 and 1996                   11

Statements of Income for the years ended
  December 31, 1997, 1996 and 1995                             12

Statement of Changes in Partners' Equity for
  the three years ended December 31, 1997                      13

Statements of Cash Flows for the years ended
  December 31, 1997, 1996 and 1995                             14

Notes to Financial Statements                                 15-19
</TABLE>


                                       9
<PAGE>   10

                        [ARTHUR ANDERSEN LLP LETTERHEAD]


                    REPORT OF INDEPENDENT PUBLIC ACCOUNTANTS

To the Partners of
  Del Taco Restaurant Properties, I:

We have audited the accompanying balance sheets of DEL TACO RESTAURANT
PROPERTIES I (a California limited partnership) as of December 31, 1997 and
1996, and the related statements of income, changes in partners' equity and
cash flows for each of three years in the period ended December 31, 1997. These
financial statements are the responsibility of the Partnership's management.
Our responsibility is to express an opinion on these financial statements based
on our audits.

We conducted our audits in accordance with generally accepted auditing
standards. Those standards require that we plan and perform the audit to obtain
reasonable assurance about whether the financial statements are free of
material misstatement. An audit includes examining, on a test basis, evidence
supporting the amounts and disclosures in the financial statements. An audit
also includes assessing the accounting principles used and significant
estimates made by management, as well as evaluating the overall financial
statement presentation. We believe that our audits provide a reasonable basis
for our opinion.

In our opinion, the financial statements referred to above present fairly, in
all material respects, the financial position of Del Taco Restaurant Properties
I as of December 31, 1997 and 1996, and the results of its operations and its
cash flows, for each of the three years in the period ended December 31, 1997,
in conformity with generally accepted accounting principles.

Our audit was made for the purpose of forming an opinion on the basic financial
statements taken as a whole. The schedule in the index of financial statements
is presented for purposes of complying with the Securities and Exchange
Commissions rules and is not part of the basic financial statements. This
schedule has been subjected to the auditing procedures applied in the audit of
the basic financial statements and, in our opinion, fairly states, in all
material respects, the financial data required to be set forth therein in
relation to the basic financial statements taken as a whole.

                                        /s/ ARTHUR ANDERSEN LLP
                                        ------------------------
                                          ARTHUR ANDERSEN LLP


Orange County, California
February 10, 1998

                                       10
<PAGE>   11
                        DEL TACO RESTAURANT PROPERTIES I

                                 BALANCE SHEETS


<TABLE>
<CAPTION>
                                                                         DECEMBER 31,
                                                                     1997             1996
                                                                 ------------     ------------
<S>                                                              <C>              <C>         

                                     ASSETS

CURRENT ASSETS:
  Cash                                                           $    143,280     $    130,996
  Receivable from Del Taco, Inc. (Note 5)                              42,601           38,478
  Deposits                                                                600              600
                                                                 ------------     ------------
     Total current assets                                             186,481          170,074
                                                                 ------------     ------------

PROPERTY AND EQUIPMENT, AT COST (NOTE 1)
  Land and improvements                                             1,852,482        1,852,482
  Buildings and improvements                                        1,013,134        1,013,134
  Machinery and equipment                                           1,136,026        1,136,026
                                                                 ------------     ------------
                                                                    4,001,642        4,001,642
    Less: accumulated depreciation                                  1,672,315        1,628,543
                                                                 ------------     ------------
                                                                    2,329,327        2,373,099
                                                                 ------------     ------------

                                                                 $  2,515,808     $  2,543,173
                                                                 ============     ============


                        LIABILITIES AND PARTNERS' EQUITY

CURRENT LIABILITIES:
  Payable to Limited Partners                                    $     12,690     $     11,319
  Accounts Payable                                                      6,531            3,000
                                                                 ------------     ------------
     Total current liabilities                                         19,221           14,319
                                                                 ------------     ------------

PARTNERS' EQUITY (NOTE 2)
  Limited Partners                                                  2,231,634        2,263,579
  General Partner - Del Taco, Inc.                                    264,953          265,275
                                                                 ------------     ------------
                                                                    2,496,587        2,528,854
                                                                 ------------     ------------

                                                                 $  2,515,808     $  2,543,173
                                                                 ============     ============
</TABLE>


                     The accompanying notes are an integral
                       part of these financial statements.


                                       11
<PAGE>   12
                        DEL TACO RESTAURANT PROPERTIES I

                              STATEMENTS OF INCOME


<TABLE>
<CAPTION>
                                                   YEAR ENDED
                                                  DECEMBER 31,
                                       1997           1996           1995
                                   ------------   ------------   ------------
<S>                                <C>            <C>            <C>         

REVENUES:
  Rent (Note 4)                    $    487,280   $    452,203   $    436,262
  Interest                                3,359          2,265          2,279
  Other                                   1,750            637            450
                                   ------------   ------------   ------------
                                        492,389        455,105        438,991
                                   ------------   ------------   ------------
EXPENSES:
  General and administrative             45,261         45,943         42,441
  Depreciation                           43,772         43,775        121,530
                                   ------------   ------------   ------------
                                         89,033         89,718        163,971
                                   ------------   ------------   ------------

Net Income                         $    403,356   $    365,387   $    275,020
                                   ============   ============   ============

Net Income per Limited
  Partnership Unit (Note 1)        $      45.63   $      41.34   $      31.11
                                   ============   ============   ============
</TABLE>


                     The accompanying notes are an integral
                       part of these financial statements.


                                       12
<PAGE>   13
                        DEL TACO RESTAURANT PROPERTIES I

                    STATEMENT OF CHANGES IN PARTNERS' EQUITY

                       THREE YEARS ENDED DECEMBER 31, 1997


<TABLE>
<CAPTION>
                                                Limited Partners             
                                        ------------------------------          General
                                           Units              Amount            Partner             Total
                                        -----------        -----------        -----------        -----------
<S>                                     <C>                <C>                <C>                <C>        

Balance, December 31, 1994                    8,751        $ 2,421,394        $   266,869        $ 2,688,263
  Net income                                                   272,270              2,750            275,020
  Cash distributions (Note 7)                                 (399,909)            (4,039)          (403,948)
                                        -----------        -------------------------------------------------

Balance, December 31, 1995                    8,751          2,293,755            265,580          2,559,335
  Net income                                                   361,733              3,654            365,387
  Cash distributions (Note 7)                                 (391,909)            (3,959)          (395,868)
                                        -----------        -------------------------------------------------

Balance, December 31, 1996                    8,751          2,263,579            265,275          2,528,854
  Net income                                                   399,322              4,034            403,356
  Cash distributions (Note 7)                                 (431,267)            (4,356)          (435,623)
                                        -----------        -------------------------------------------------

Balance, December 31, 1997                    8,751        $ 2,231,634        $   264,953        $ 2,496,587
                                        ===========        =================================================
</TABLE>


                     The accompanying notes are an integral
                       part of these financial statements.


                                       13
<PAGE>   14
                        DEL TACO RESTAURANT PROPERTIES I

                            STATEMENTS OF CASH FLOWS


<TABLE>
<CAPTION>
                                                               YEAR ENDED
                                                              DECEMBER 31,
                                                 1997              1996               1995
                                             ------------     ------------     ------------
<S>                                          <C>              <C>              <C>         
CASH FLOWS FROM OPERATING ACTIVITIES:

Net income                                   $    403,356     $    365,387     $    275,020
Adjustments to reconcile net income to
 net cash provided by operating
 activities:
    Depreciation                                   43,772           43,775          121,530
    Increase (decrease) in payable to
     Limited Partners                               1,371            2,421           (3,272)
    (Increase) decrease in receivable
     from General Partner                          (4,123)          (1,824)           4,056
    Increase in accounts
     payable                                        3,531            2,093              906
                                             ------------     ------------     ------------

     Net cash provided by operating
      activities                                  447,907          411,852          398,240


CASH FLOWS FROM FINANCING ACTIVITIES:

Cash distributions to partners                   (435,623)        (395,868)        (403,948)
                                             ------------     ------------     ------------

Net increase (decrease) in cash                    12,284           15,984           (5,708)

Beginning cash balance                            130,996          115,012          120,720
                                             ------------     ------------     ------------

Ending cash balance                          $    143,280     $    130,996     $    115,012
                                             ============     ============     ============
</TABLE>


                          The accompanying notes are an
                  integral part of these financial statements.


                                       14
<PAGE>   15
                        DEL TACO RESTAURANT PROPERTIES I

                          NOTES TO FINANCIAL STATEMENTS

                                DECEMBER 31, 1997


NOTE 1 - ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

THE PARTNERSHIP: Del Taco Restaurant Properties I (a California limited
partnership) was formed on November 30, 1982, for the purpose of acquiring real
property in California for construction of six Mexican-American restaurants to
be leased under long-term agreements to Del Taco, Inc. (General Partner for
operation under the Del Taco trade name). As of February 14, 1986, all six
restaurants had commenced operation on acquired properties.

BASIS OF ACCOUNTING: The Partnership utilizes the accrual method of accounting
for transactions relating to the business of the Partnership. Distributions are
made to the General and Limited Partners in accordance with the provisions of
the Partnership Agreement (see Note 2).

PROPERTY AND EQUIPMENT: Property and equipment is stated at cost. Depreciation
is computed using the straight-line method over estimated useful lives which are
20 years for land improvements, 35 years for buildings and improvements, and 10
years for machinery and equipment.

In fiscal 1996, the Registrant adopted Statement of Financial Accounting
Standards (SFAS) No. 121, "Accounting for the Impairment of Long Lived Assets
and for Long Lived Assets to be Disposed of." SFAS 121 requires that long-lived
assets be reviewed for impairment whenever events or changes in circumstances
indicate that the carrying value of the asset may not be recoverable. In
evaluating long-lived assets held for use, an impairment loss is recognized if
the sum of the expected future cash flows (undiscounted and without interest
charges) is less than the carrying value of the asset. Once a determination has
been made that an impairment loss should be recognized for long-lived assets,
various assumptions and estimates are used to determine fair value including,
among others, estimated costs of construction and development, recent sales of
comparable properties and the opinions of fair value prepared by independent
real estate appraisers. Long-lived assets to be disposed of are reported at the
lower of carrying amount or fair value less cost to sell.

The adoption of SFAS No. 121 did not have a material effect on the Registrant's
financial statements.


                                       15
<PAGE>   16
DEL TACO RESTAURANT PROPERTIES I
NOTES TO FINANCIAL STATEMENTS - CONTINUED
DECEMBER 31, 1997


NOTE 1 - ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES -
         (CONTINUED)

INCOME TAXES: No provision has been made for federal or state income taxes on
Partnership net income, since the Partnership is not subject to income tax.
Partnership income is includable in the taxable income of the individual
partners as required under applicable income tax laws. Certain items, primarily
related to depreciation methods, are accounted for differently for income tax
reporting purposes (see Note 6).

NET INCOME PER LIMITED PARTNERSHIP UNIT: Net income per Limited Partnership Unit
is based upon the weighted average number of Units outstanding during the period
which amounted to 8,751 for all years presented.

USE OF ESTIMATES: The preparation of the financial statements in conformity with
generally accepted accounting principles requires management to make certain
estimates and assumptions that affect the reported amounts of assets and
liabilities at the date of the financial statements and the reported amounts of
revenues and expenses during the reporting period. Actual results could differ
from those estimates.

NOTE 2 - PARTNERS' EQUITY

Pursuant to the Partnership Agreement, annual partnership net income is
allocated one percent to the General Partner and 99 percent to the Limited
Partners. A Partnership net loss in any year will be allocated 24 percent to the
General Partner and 76 percent to the Limited Partners until the losses so
allocated equal income previously allocated. Any additional losses will be
allocated one percent to the General Partner and 99 percent to the Limited
Partners.

Partnership gains from any sale or refinancing will be allocated one percent to
the General Partner and 99 percent to the Limited Partners until allocated gains
and profits equal losses. Additional gains will be allocated 24 percent to the
General Partner and 76 percent to the Limited Partners.

In 1986, the General Partner contributed additional capital of $280,000 to the
Partnership in order to provide funds necessary to complete the sixth and final
restaurant.


                                       16
<PAGE>   17
DEL TACO RESTAURANT PROPERTIES I
NOTES TO FINANCIAL STATEMENTS - CONTINUED
DECEMBER 31, 1997


NOTE 3 - SITE ACQUISITION AND DEVELOPMENT FEE

Under terms of the Partnership Agreement, the General Partner is entitled to
receive a site acquisition and development fee in an amount equal to the lesser
of five percent of the cost of the related property or $30,000. The fee shall be
for service rendered in connection with site selection and the design and
supervision of construction of improvements to acquired properties. No site
acquisition and development fees were paid in 1997, 1996 and 1995.

NOTE 4 - LEASING ACTIVITIES

The Registrant leases certain properties for operation of restaurants to Del
Taco, Inc. (General Partner) on a triple net basis. The leases are for terms of
35 years commencing with the completion of the restaurant facility located on
each Property and require monthly rentals equal to 12 percent of the gross sales
of the restaurants. There is no minimum rental under any of the Leases. The
Registrant had a total of six Properties leased as of December 31, 1997, 1996
and 1995, two of which have been subleased to Del Taco franchisees (one of which
is affiliated with Del Taco, Inc.)

The five restaurants operated by or affiliated with Del Taco, for which the
Registrant is the lessor, had combined, unaudited sales of $3,447,723,
$3,229,726, and $3,119,197 and unaudited net income of $149,010, $77,336 and
$75,564 for the years ended December 31, 1997, 1996 and 1995, respectively. Net
income by restaurant includes charges for general and administrative expenses
incurred in connection with supervision of restaurant operations and interest
expense. The one restaurant operated by a Del Taco franchisee, for which the
Registrant is the lessor, had unaudited sales of $612,943, $538,632 and $516,320
for the years ended December 31, 1997, 1996 and 1995, respectively.

The Elkhorn Boulevard restaurant in Sacramento, California had unaudited net
losses of $13,302, $18,566 and $10,633 for the years ended December 31, 1997,
1996 and 1995, respectively.

NOTE 5 - RELATED PARTIES

The receivable from Del Taco consists of rent accrued for the month of December
1997. The rent receivable was collected on January 17, 1998.

The General Partner received $4,356 in distributions relating to its one percent
interest in the Registrant for the year ended December 31, 1997.


                                       17
<PAGE>   18
DEL TACO RESTAURANT PROPERTIES I
NOTES TO FINANCIAL STATEMENTS - CONTINUED
DECEMBER 31, 1997


NOTE 5 - RELATED PARTIES (Continued)

Del Taco, Inc. serves in the capacity of general partner in other partnerships
which are engaged in the business of operating restaurants, and three other
partnerships which were formed for the purpose of acquiring real property in
California for construction of Mexican-American restaurants for lease under
long-term agreements to Del Taco, Inc. for operation under the Del Taco trade
name.

NOTE 6 - INCOME TAXES

A reconciliation of financial statement net income to taxable income for each of
the periods is as follows:

<TABLE>
<CAPTION>
                                            1997              1996             1995
                                          ---------        ---------        ---------
<S>                                       <C>              <C>              <C>      

Net income per financial statements       $ 403,356        $ 365,387        $ 275,020

Excess book depreciation                     (2,265)          (4,780)          72,975
                                          ---------        ---------        ---------

Taxable income                            $ 401,091        $ 360,607        $ 347,995
                                          =========        =========        =========
</TABLE>

A reconciliation of partnership equity per the financial statements to net worth
for tax purposes as of December 31, 1997, is as follows:

<TABLE>
<S>                                          <C>       
Partners' equity per financial
  statements                                 $2,496,587

Issue costs of Limited Partnership
  Units capitalized for tax purposes            637,325

Excess tax depreciation                        (137,333)

Other                                               235
                                             ----------
Net worth for tax purposes                   $2,996,814
                                             ==========
</TABLE>


                                       18
<PAGE>   19
DEL TACO RESTAURANT PROPERTIES I
NOTES TO FINANCIAL STATEMENTS - CONTINUED
DECEMBER 31, 1997


NOTE 7 - CASH DISTRIBUTIONS TO LIMITED PARTNERS

Cash distributions paid to Limited Partners for the three years ended December
31, 1997 were as follows:

<TABLE>
<CAPTION>
                                                    Weighted         Number of 
                                                     Average            Units   
                        Distributions per           Number of        Outstanding
                       Limited Partnership            Units          at the End 
 Quarter Ended                Unit                Outstanding        of Quarter 
 -------------         -------------------        -----------        -----------
<S>                    <C>                       <C>                 <C>   

December 31, 1994           $ 11.70                  8,751              8,751
March 31, 1995                10.90                  8,751              8,751
June 30, 1995                 10.47                  8,751              8,751
September 30, 1995            12.63                  8,751              8,751
                            -------                                  
  Total paid in 1995        $ 45.70                                  
                            =======                                  
                                                                     
December 31, 1995           $ 11.46                  8,751              8,751
March 31, 1996                10.68                  8,751              8,751
June 30, 1996                 10.21                  8,751              8,751
September 30, 1996            12.47                  8,751              8,751
                            -------                                  
  Total paid in 1996        $ 44.82                                  
                            =======                                  
                                                                     
December 31, 1996           $ 12.63                  8,751              8,751
March 31, 1997                11.59                  8,751              8,751
June 30, 1997                 11.19                  8,751              8,751
September 30, 1997            13.87                  8,751              8,751
                            -------                                
  Total paid in 1997        $ 49.28              
                            =======
</TABLE>

Cash distributions per Limited Partnership Unit were calculated based upon the
weighted average number of units outstanding for each quarter and were paid from
operations. Cash distributions for the quarter ended December 31, 1997 amounted
to $11.59 per Limited Partnership Unit and were paid January 31, 1998.


                                       19
<PAGE>   20
                                    PART III


ITEM 9. DISAGREEMENTS ON ACCOUNTING AND FINANCIAL DISCLOSURE

None

ITEM 10. DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT'S GENERAL PARTNER

(a) & (b) The executive officers and directors of the General Partner and their
ages are set forth below:


<TABLE>
<CAPTION>
Name                         Title                                          Age
----                         -----                                          ---
<S>                          <C>                                            <C>

Kevin K. Moriarty            Director, Chairman and Chief Executive Officer  51

Paul W. Hitzelberger         Executive Vice President, Brand Strategy and
                                Franchise Relations/Development              53

Robert Terrano               Executive Vice President and
                               Chief Financial Officer                       42

James D. Stoops              Executive Vice President, Operations            45

Janet D. Simmons             Senior Vice President, Purchasing               41

Michael L. Annis             Vice President, Secretary and General Counsel   51

C. Douglas Mitchell          Vice President and Corporate Controller         47
</TABLE>


The above referenced executive officers and directors of the General Partner
will hold office until the annual meeting of its shareholders and directors,
which is scheduled for the later part of 1998.

(c)   None

(d)   No family relationship exists between any such director or executive
      officer of the General Partner.

(e)   The following is an account of the business experience during the past
      five years of each such director and executive officer:


                                       20
<PAGE>   21
Kevin K. Moriarty, Director, Chairman and Chief Executive Officer of Del Taco,
Inc. Mr. Moriarty began his career with Burger King Corporation in 1974 in
Operations Unit Management. In 1983, he was promoted to Area Manager in New
York, and was subsequently promoted to the Regional Vice President, Chicago
Region in 1985. In 1988, he became Executive Vice President and General Manager
of the North Central Division. Mr. Moriarty served in that position until 1990
when he joined Del Taco, Inc. as President and Chief Executive Officer on July
31, 1990. Mr. Moriarty has served as a Director of the General Partner since
1990.

Paul W. Hitzelberger, Executive Vice President, Brand Strategy and Franchise
Relations/Development of Del Taco, Inc. He was appointed to his current position
in December 1995. Previously, Mr. Hitzelberger was Executive Vice President,
Marketing from February 1991 and Vice President, Marketing from 1989 to 1991.
Mr. Hitzelberger has responsibility for franchise development, relations and
training and will oversee public relations and training for the corporation.
From September 1988 through September 1989, Mr. Hitzelberger was Chief Executive
Officer of Environmental Marketing Group. Prior to that, Mr. Hitzelberger was a
Vice President of Del Taco, Inc. Prior to joining Del Taco, Inc., he served as
Vice President - Marketing at the department store division of Lucky Stores,
Inc., a major supermarket retailer. Prior to his position with Lucky, Mr.
Hitzelberger held various positions in marketing and retailing at Wallpapers to
Go, Inc., a division of General Mills, Inc., and Coast to Coast Stores, Inc. a
subsidiary of Household Merchandising, Inc. Mr. Hitzelberger received a Master
of Business Administration degree from Loyola University in Chicago, Illinois.

Robert J. Terrano, Executive Vice President and Chief Financial Officer of Del
Taco, Inc. From May 1994 to April 1995, Mr. Terrano served as Chief Financial
Officer for Denny's, Inc. in Spartanburg, S.C. From August 1983 to May 1994, he
served with Burger King Corporation, Miami Florida, in a variety of positions,
most recently as Division Controller. Mr. Terrano joined Del Taco, Inc. in April
1995.

James D. Stoops, Executive Vice President, Operations of Del Taco, Inc. From
1968 to 1991, Mr. Stoops served in a wide variety of Operations positions with
Burger King Corporation with increasing levels of responsibility. In 1985, Mr.
Stoops was appointed Region Vice President/General Manager for the New York
region and served in that position until October of 1990. In January of 1991, he
joined Del Taco, Inc. in his current post.

Janet D. Simmons, Senior Vice President, Purchasing of Del Taco, Inc. From 1979
to 1986, Ms. Simmons was with Denny's Incorporated. She served in the Research
and Development department in a variety of positions until 1982 when she was
promoted to the position of Purchasing Agent. Ms. Simmons was hired in 1986 as
Manager of Contract Purchasing with Carl Karcher Enterprises, a post she held
until March 1990 when she became Vice President, Purchasing for Del Taco, Inc.
Ms. Simmons has a Bachelor of Science degree in Foods and Nutrition from Cal
State Polytechnic University in Pomona, California.


                                       21
<PAGE>   22
Michael L. Annis, Vice President, Secretary and General Counsel of Del Taco,
Inc. From 1981 to 1986 Mr. Annis served as Regional Real Estate Manager and
Director of Real Estate Services with Taco Bell, Inc. In 1986 he served as
Regional General Manager with Quaker State Minit Lube. In January of 1987 Mr.
Annis joined Red Robin International, Inc. as General Counsel and was
subsequently promoted to Vice President/Secretary and later Vice President Real
Estate Development/Secretary and General Counsel, the position he held until
joining Del Taco, Inc. in December of 1993. Mr. Annis received his J.D. Degree
from Whittier College.

C. Douglas Mitchell, Vice President and Corporate Controller. Mr. Mitchell
joined Del Taco, Inc. in August of 1994 as Controller and was promoted to his
current position in January 1996. From 1990 to 1994, Mr. Mitchell was a Senior
Audit Manager with Coopers & Lybrand. Prior to 1990, Mr. Mitchell held various
positions in finance and accounting with the Geneva Companies (a subsidiary of
Chemical Bank), Zaremba Corporation (a real estate developer) and The Dexter
Corporation (an international manufacturer of specialty materials). Mr. Mitchell
has a Bachelor of Science degree with a major in accounting from the University
of Southern California.

ITEM 11. MANAGEMENT REMUNERATION AND TRANSACTIONS

The Registrant has no executive officers or directors and pays no direct
remuneration to any executive officer or director of its General Partner. The
Registrant has not issued any options or stock appreciation rights to any
executive officer or director of its General Partner, nor does the Registrant
propose to pay any annuity, pension or retirement benefits to any executive
officer or director of its General Partner. The Registrant has no plan, nor does
the Registrant presently propose a plan, which will result in any remuneration
being paid to any executive officer or director of the General Partner upon
termination of employment.


                                       22
<PAGE>   23
ITEM 12. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

(a)   No person of record currently owns more than five percent of Limited
      Partnership Units of the Registrant, nor was any person known of by the
      Registrant to own of record and beneficially, or beneficially only, more
      than five percent of such securities.

(b)   Neither Del Taco, Inc., nor any executive officer or director of Del Taco,
      Inc. owns any Limited Partnership Units of the Registrant.

(c)   The Registrant knows of no contractual arrangements, the operation or the
      terms of which may at a subsequent date result in a change in control of
      the Registrant, except for provisions in the Partnership Agreement
      providing for removal of the General Partner by holders of a majority of
      the Limited Partnership Units and if a material event of default occurs
      under the financing agreements of the General Partner.

ITEM 13. CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS

(a)   No transactions have occurred between the Registrant and any executive
      officer or director of its General Partner.

      During 1997, the following transactions occurred between the Registrant
      and the General Partner pursuant to the terms of the Partnership
      Agreement.

      (1)   The General Partner earned $4,034 as its one percent share of the
            net income of the Registrant.

      (2)   The General Partner received $4,356 in distributions relating to its
            one percent interest in the Registrant.

(b)   During 1997, the Registrant had no business relationships with any entity
      of a type required to be reported under this item.

(c)   Neither the General Partner, any director or officer of the General
      Partner or any associate of any such person, was indebted to the
      Registrant at any time during 1997 for any amount in excess of $60,000.

(d)   Not applicable.


                                       23
<PAGE>   24
                                     PART IV


ITEM 14(a)(1) AND (2). EXHIBITS, FINANCIAL STATEMENTS SCHEDULES, AND REPORTS ON
                       FORM 8-K


      Financial statement schedules:

            Schedule III - Real Estate and Accumulated Depreciation

      Financial statement schedules other than those referred to above have been
      omitted because they are not applicable or not required.


(b)   No reports on Form 8-K were filed during the last quarter of 1997.

(c)   Exhibits required by Item 601 of Regulation S-K:

      1.    Incorporated herein by reference, Restated Certificate and Agreement
            of Limited Partnership of Del Taco Restaurant Properties I filed as
            Exhibit 3.01 to Registrant's Registration Statement on Form S-11 as
            filed with the Securities and Exchange Commission on December 17,
            1982.

      2.    Incorporated herein by reference, Amendment to Restated Certificate
            and Agreement of Limited Partnership of Del Taco Restaurant
            Properties I.

      3.    Incorporated herein by reference, Form of Standard Lease to be
            entered into by Registrant and Del Taco, Inc., as lessee, filed as
            Exhibit 10.02 to Registrant's Registration Statement on Form S-11 as
            filed with the Securities and Exchange Commission on December 17,
            1982.


                                       24
<PAGE>   25
                           DEL TACO I - SCHEDULE III
                    REAL ESTATE AND ACCUMULATED DEPRECIATION
                                DECEMBER 31, 1997
 
 
<TABLE>
<CAPTION>
                                                                     Cost capitalized                    Gross amount at
                                                  Initial cost        subsequent to                      which carried at
                                                   to company          acquisition                      close of period  
         Description           Encumbrances      ------------------------------------------------------------------------
                                                    Buildings                                            Buildings & land
      (All Restaurants)                               & land             Improve-          Carrying        improvements  
                                                  improvements            ments              costs            Total
-------------------------------------------------------------------------------------------------------------------------
<S>                            <C>               <C>                   <C>               <C>             <C>             
Rialto,  CA                      $  --           $   274,837           $   150,310       $  --              $ 425,147    
Moreno Valley, CA                   --               353,557               193,362          --                546,919    
La Verne, CA                        --               452,423               247,433          --                699,856    
Rancho Cucamonga, CA                --               293,817               160,690          --                454,507    
Sacramento, CA                      --               260,516               142,478          --                402,994    
Rancho Cucamonga, CA                --               217,332               118,861                            336,193    
                               ------------------------------------------------------------------------------------------
                                 $  --           $ 1,852,482           $ 1,013,134       $  --             $ 2,865,616    
                               ==========================================================================================
</TABLE>


<TABLE>
<CAPTION>
                               
                               
                                                                               Life on which     
         Description           Accumulated         Date of         Date     depreciation in latest
                               depreciation     construction     acquired      income statement
      (All Restaurants)                                                          is computed
                               
--------------------------------------------------------------------------------------------------
<S>                            <C>              <C>              <C>        <C>     
Victorville,  CA                 $ 79,565            1984           1984       20 (LI), 35 (BI) 
Colton, CA                        102,354            1985           1985       20 (LI), 35 (BI) 
Palmdale, CA                      130,975            1985           1985       20 (LI), 35 (BI) 
Pedley, CA                         85,059            1985           1985       20 (LI), 35 (BI) 
Thousand Palms, CA                 75,419            1985           1985       20 (LI), 35 (BI) 
                                   62,917            1985           1985       20 (LI), 35 (BI)
                               ----------
                                 $536,289
                               ==========
</TABLE>



<TABLE>
<CAPTION>
                                                                Accumulated
                                           Restaurants          Depreciation 
                                          ------------          ------------
<S>                                       <C>                   <C>         
                                                                        --
Balances at December 31, 1994:            $  2,865,616          $    404,973
   Acquisitions                                   --                  43,772
   Sales                                          --                    --
                                          ----------------------------------
Balances at December 31, 1995:               2,865,616               448,745
   Acquisitions                                   --                  43,772
   Sales                                          --                    --
                                          ----------------------------------
Balances at December 31, 1996:               2,865,616               492,517
   Acquisitions                                   --                  43,772
   Sales                                          --                    --
                                          ----------------------------------
Balances at December 31, 1997:            $  2,865,616          $    536,289
                                          ==================================
</TABLE>


                                       25
<PAGE>   26

                                   SIGNATURES


Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange
Act of 1934, the Registrant has duly caused this report to be signed on its
behalf by the undersigned, thereunto duly authorized.



                                            DEL TACO RESTAURANT PROPERTIES I
                                            a California limited partnership
                                            Registrant

                                            Del Taco, Inc.
                                            General Partner



Date March 07, 1998                         Kevin K. Moriarty
     --------------                         -----------------
                                            Kevin K. Moriarty
                                            Director, Chairman and Chief
                                            Executive Officer



Date March 07, 1998                         Michael L. Annis
     --------------                         ----------------
                                            Michael L. Annis
                                            Vice President, Secretary and
                                            General Counsel




Date March 07, 1998                         Robert J. Terrano
     --------------                         -----------------
                                            Robert J. Terrano
                                            Executive Vice President and
                                            Chief Financial Officer




Date March 07, 1998                         C. Douglas Mitchell
     --------------                         -------------------
                                            C. Douglas Mitchell
                                            Vice President and Corporate
                                            Controller


                                       26