INTERIM FINANCIAL INFORMATION (Policies)	9 Months Ended
INTERIM FINANCIAL INFORMATION (Policies)	Sep. 30, 2012
Business and Organization	*Business and Organization* Group 1 Automotive, Inc., a Delaware corporation, through its subsidiaries, is a leading operator in the automotive retailing industry with operations in 15 states in the United States of America (“U.S.”) and 11 towns in the United Kingdom (“U.K.”). Group 1 Automotive, Inc. and its subsidiaries are herein collectively referred to as the “Company.” The Company, through its regions, sells new and used cars and light trucks; arranges related vehicle financing; service and insurance contracts; provides automotive maintenance and repair services; and sells vehicle parts. As of September 30, 2012, the Company’s U.S. retail network consisted of the following two regions (with the number of dealerships they comprised): (a) the East (47 dealerships in Alabama, Florida, Georgia, Louisiana, Maryland, Massachusetts, Mississippi, New Hampshire, New Jersey, New York and South Carolina), and (b) the West (64 dealerships in California, Kansas, Oklahoma, and Texas). Each region is managed by a regional vice president who reports directly to the Company’s Chief Executive Officer and is responsible for the overall performance of their regions, as well as for overseeing the market directors and dealership general managers that report to them. Each region is also managed by a regional chief financial officer who reports directly to the Company’s Chief Financial Officer. The Company’s 11 dealerships in the U.K. are also managed locally with direct reporting responsibilities to the Company’s corporate management team.
Basis of Presentation	*Basis of Presentation* The accompanying unaudited condensed Consolidated Financial Statements have been prepared in accordance with accounting principles generally accepted in the U.S. for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by accounting principles generally accepted in the U.S. for complete financial statements. In the opinion of management, all adjustments of a normal and recurring nature considered necessary for a fair presentation have been included in the accompanying unaudited condensed Consolidated Financial Statements. Due to seasonality and other factors, the results of operations for the interim period are not necessarily indicative of the results that will be realized for the entire fiscal year. For further information, refer to the Consolidated Financial Statements and footnotes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2011 (“2011 Form 10-K”). All acquisitions of dealerships completed during the periods presented have been accounted for using the purchase method of accounting and their results of operations are included from the effective dates of the closings of the respective acquisitions. The allocations of purchase price to the assets acquired and liabilities assumed are assigned and recorded based on estimates of fair value. All intercompany balances and transactions have been eliminated in consolidation.
Recent Accounting Pronouncements	*Recent Accounting Pronouncements* In May 2011, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2011-04, Amendments to Achieve Common Fair Value Measurement and Disclosure Requirements in U.S. GAAP and IFRSs. This update changes certain fair value measurement principles and enhances the disclosure requirements, particularly Level 3 fair value measurements. The Company adopted ASU 2011-04 as of March 31, 2012 and it did not have a material impact on the Company’s consolidated financial position or results of operations. In September 2011, the FASB issued ASU 2011-08, Testing Goodwill for Impairment. This update permits an entity to first assess qualitative factors to determine whether it is more likely than not (likelihood more than 50%) that the fair value of a reporting unit is less than its carrying amount as a basis for determining whether it is necessary to perform the two-step goodwill impairment test. The Company adopted ASU 2011-08 as of March 31, 2012 and it did not have an impact on the Company’s consolidated financial position or results of operations. In December 2011, the FASB issued ASU 2011-10, Disclosures about Offsetting Assets and Liabilities. This update requires additional disclosures related to offsetting either in accordance with U.S. generally accepted accounting principles (“GAAP”) or master netting arrangements. This ASU is effective for reporting periods beginning after January 1, 2013. The Company does not expect this update to have a material effect on its consolidated financial statements. In July 2012, the FASB issued ASU 2012-02, Testing Indefinite-Lived Intangible Assets for Impairment. This update gives an entity the option to first assess qualitative factors to determine whether it is more likely than not (likelihood more than 50%) that the fair value of the indefinite-lived intangible assets is impaired as a basis for determining whether it is necessary to revalue the fair value of the impaired assets. This ASU is effective for annual and interim impairment tests performed for fiscal years beginning after September 15, 2012. The Company does not expect this update to have a material effect on its consolidated financial statements.

Disclosure of accounting policy for completed business combinations (purchase method, acquisition method or combination of entities under common control). This accounting policy may include a general discussion of the purchase method or acquisition method of accounting (including for example, the treatment accorded contingent consideration, the identification of assets and liabilities, the purchase price allocation process, how the fair values of acquired assets and liabilities are determined) and the entity's specific application thereof. An entity that acquires another entity in a leveraged buyout transaction generally discloses the accounting policy followed by the acquiring entity in determining the basis used to value its interest in the acquired entity, and the rationale for that accounting policy.

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