EXHIBIT 23 CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM We consent to the incorporation by reference in Registration Statements No. 333-29203 and No. 333-60909 on form S-8 of our report dated March 25, 2005, relating to the financial statements and financial statement schedules of Core Molding Technologies, Inc. and subsidiaries appearing in this Annual Report on Form 10-K of Core Molding Technologies, Inc. for the year ended December 31, 2004. /s/ Deloitte & Touche LLP - ------------------------- Columbus, Ohio March 25, 2005 47